As electric vehicle(EV)sales grew approximately 50%year-over-year,surpassing 3.2 million units in 2020,the“roaring era”of EV is around the corner.To meet the increasing demand for low cost and high energy density ba...As electric vehicle(EV)sales grew approximately 50%year-over-year,surpassing 3.2 million units in 2020,the“roaring era”of EV is around the corner.To meet the increasing demand for low cost and high energy density batteries,anode-free configuration,with no heavy and voluminous host material on the current collector,has been proposed and further investigated.Nevertheless,it always suffers from several non-negligible“bottlenecks”,such as fragile solid electrolyte interface,deteriorated cycling reversibility,and uncontrolled dendrite formation.Inspired by the“compensatory effect”of some disabled people with other specific functions strengthened to make up for their inconvenience,corresponding quasi-compensatory measures after anode removal,involving dimensional compensation,SEI robustness compensation,lithio-philicity compensation,and lithium source compensation,have been carried out and achieved significant battery performance enhancement.In this review,the chemistry,challenges,and rationally designed“quasi-compensatory effect”associated with anode-free lithium-ion battery are systematically discussed with several possible R&D directions that may aid,direct,or facilitate future research on lithium storage in anode-free configuration essentially emphasized.展开更多
The presence of sealed or semi-sealed,multiscale natural fracture systems appears to be crucial for the successful stimulation of deep reservoirs.To explore the reaction of such systems to reservoir stimulation,a new ...The presence of sealed or semi-sealed,multiscale natural fracture systems appears to be crucial for the successful stimulation of deep reservoirs.To explore the reaction of such systems to reservoir stimulation,a new numerical simulation approach for hydraulic stimulation has been developed,trying to establish a realistic model of the physics involved.Our new model successfully reproduces dynamic fracture activation,network generation,and overall reservoir permeability enhancement.Its outputs indicate that natural fractures facilitate stimulation far beyond the near-wellbore area,and can significantly improve the hydraulic conductivity of unconventional geo-energy reservoirs.According to our model,the fracture activation patterns are jointly determined by the occurrence of natural fractures and the in situ stress.High-density natural fractures,high-fluid pressure,and low effective stress environments promote the formation of complex fracture networks during stimulation.Multistage or multicluster fracturing treatments with an appropriate spacing also increase the stimulated reservoir area(SRA).The simulation scheme demonstrated in this work offers the possibility to elucidate the complex multiphysical couplings seen in the field through detailed site-specific modeling.展开更多
The discovery of chirped pulse amplification has led to great improvements in laser technology,enabling energetic laser beams to be compressed to pulse durations of tens of femtoseconds and focused to a few micrometer...The discovery of chirped pulse amplification has led to great improvements in laser technology,enabling energetic laser beams to be compressed to pulse durations of tens of femtoseconds and focused to a few micrometers.Protons with energies of tens of MeV can be accelerated using,for instance,target normal sheath acceleration and focused on secondary targets.Under such conditions,nuclear reactions can occur,with the production of radioisotopes suitable for medical application.The use of high-repetition lasers to produce such isotopes is competitive with conventional methods mostly based on accelerators.In this paper,we study the production of^(67)Cu,^(63)Zn,^(18)F,and^(11)C,which are currently used in positron emission tomography and other applications.At the same time,we study the reactions^(10)B(p,α)^(7)Be and^(70)Zn(p,4n)^(67)Ga to put further constraints on the proton distributions at different angles,as well as the reaction^(11)B(p,α)^(8)Be relevant for energy production.The experiment was performed at the 1 PW laser facility at VegaⅢin Salamanca,Spain.Angular distributions of radioisotopes in the forward(with respect to the laser direction)and backward directions were measured using a high purity germanium detector.Our results are in reasonable agreement with numerical estimates obtained following the approach of Kimura and Bonasera[Nucl.Instrum.Methods Phys.Res.,Sect.A 637,164–170(2011)].展开更多
Recent phenomena such as pandemics,geopolitical tensions,and climate change-induced extreme weather events have caused transportation network interruptions,revealing vulnerabilities in the global supply chain.A salien...Recent phenomena such as pandemics,geopolitical tensions,and climate change-induced extreme weather events have caused transportation network interruptions,revealing vulnerabilities in the global supply chain.A salient example is the March 2021 Suez Canal blockage,which delayed 432 vessels carrying cargo valued at$92.7 billion,triggering widespread supply chain disruptions.Our ability to model the spatiotemporal ramifications of such incidents remains limited.To fill this gap,we develop an agent-based complex network model integrated with frequently updated maritime data.The Suez Canal blockage is taken as a case study.The results indicate that the effects of such blockages go beyond the directly affected countries and sectors.The Suez Canal blockage led to global losses of about$136.9($127.5–$147.3)billion,with India suffering 75%of these losses.Global losses show a nonlinear relationship with the duration of blockage and exhibit intricate trends post blockage.Our proposed model can be applied to diverse blockage scenarios,potentially acting as an earlyalert system for the ensuing supply chain impacts.Furthermore,high-resolution daily data post blockage offer valuable insights that can help nations and industries enhance their resilience against similar future events.展开更多
Variable air volume air-conditioning system(VAV system)has multiple control loops that interfered with each other,which has serious impacts on its actual operation effect.To solve this problem,the index of global hydr...Variable air volume air-conditioning system(VAV system)has multiple control loops that interfered with each other,which has serious impacts on its actual operation effect.To solve this problem,the index of global hydraulic stability,which takes the physical quantity of the pipe network pressure and the air flow rate as reference,is proposed based on Graph theory,and a pipe network model for the hydraulic calculation is built.Then,the simulation study based on the actual operation data is carried out in MATLAB.The distribution of the pressure and the air flow in the pipe network is obtained,and the action interferences among adjacent terminal boxes are analyzed based on global hydraulic stability under damper position regulation strategy(DP strategy)and fan frequency regulation strategy(FF strategy).Results indicate that the FF strategy can decrease the total change distance of the damper position compared with the DP strategy,and then the fluctuation of the pressure and the air flow can be reduced.The contribution of this study is to provide an evaluation index of global hydraulic stability,which can also be used in other air-conditioning systems with multiple terminals and multiple control loops.展开更多
In the last forty years,the rise of HIV has undoubtedly become a major concern in the field of public health,imposing significant economic burdens on affected regions.Consequently,it becomes imperative to undertake co...In the last forty years,the rise of HIV has undoubtedly become a major concern in the field of public health,imposing significant economic burdens on affected regions.Consequently,it becomes imperative to undertake comprehensive investigations into the mechanisms governing the dissemination of HIV within the human body.In this work,we have devised a mathematical model that elucidates the intricate interplay between CD4^(+)T-cells and viruses of HIV,employing the principles of fractional calculus.The production rate of CD4^(+)T-cells,like other immune cells depends on certain factors such as age,health status,and the presence of infections or diseases.Therefore,we incorporate a variable source term in the dynamics of HIV infection with a saturated incidence rate to enhance the precision of our findings.We introduce the fundamental concepts of fractional operators as a means of scrutinizing the proposed HIV model.To facilitate a deeper understanding of our system,we present an iterative scheme that elucidates the trajectories of the solution pathways of the system.We show the time series analysis of our model through numerical findings to conceptualize and understand the key factors of the system.In addition to this,we present the phase portrait and the oscillatory behavior of the system with the variation of different input parameters.This information can be utilized to predict the long-term behavior of the system,including whether it will converge to a steady state or exhibit periodic or chaotic oscillations.展开更多
Building air conditioning systems(ACs)can contribute to the stable operation of power grids by participating in peak load shaving programs,but the participants need a fast and accurate zone temperature prediction mode...Building air conditioning systems(ACs)can contribute to the stable operation of power grids by participating in peak load shaving programs,but the participants need a fast and accurate zone temperature prediction model,e.g.,the detailed room thermal-resistance(RC)model,to improve peak shaving effect and avoid obvious thermal discomfort.However,when applying the detailed room RC model to multi-zone buildings,conventional studies mostly consider the heat transfer among neighboring rooms,which contributes little to the prediction accuracy improvement,but leads to complicated model structure and heavy computation.Thus,a distributed RC model is developed for multi-zone buildings in this study.Compared to conventional models,the proposed model considers the total heat transfer between the building and the air,and ignores the heat transfer among indoor air in neighboring rooms through internal walls with heavy thermal mass,thereby having comparable temperature prediction accuracy,simpler structure,and stronger robustness.Based on the model,the effectiveness of passive pre-cooling strategies in reducing the air conditioning loads during peak periods is investigated.Results indicate that the thermal insulation performance of opaque building envelope is quite important to the flexibility enhancement of air conditioning loads.With an uninsulated building envelope,passive pre-cooling is useless for the peak load shaving.In comparison,well insulated opaque building envelope enables the building thermal mass to be utilized through passive pre-cooling,which leads to the air conditioning loads during peak periods being further reduced by about 12%.展开更多
Background and Aims:The Union Cycliste Internationale has deemed transgender female athlete’s ineligible for the female category due to concerns about performance advantages.We conducted a follow-up analysis on labor...Background and Aims:The Union Cycliste Internationale has deemed transgender female athlete’s ineligible for the female category due to concerns about performance advantages.We conducted a follow-up analysis on laboratorybased performance indicators of sports performance using data from a longitudinally assessed transgender woman athlete undergoing gender-affrming hormone therapy(GAHT).Methods:We evaluated laboratory performance indicators in transgender and cisgender women athletes using dualenergy X-ray absorptiometry scanning,handgrip strength measurement,jump testing,and cardiopulmonary exercise.Additionally,we assessed a transgender sub-elite cyclist before and after undergoing GAHT.Results:After one year of GAHT,the transgender athlete showed declines in handgrip strength(7–13%),countermovement jump(23–29%),and V̇O_(2)max(15–30%).After 3 months,several performance indicators(absolute handgrip,peak power,relative peak power,average power,relative average power,V̇O2max and relative V̇O_(2)max)were above the mean of cisgender female athletes,while others(Relative handgrip,countermovement jump and relative countermovement jump)were below.Similar trends were observed at 6 months and 1 year.Summary:This hypothetical analysis,although with limited evidence,suggests the transgender athlete could compete equitably in elite cycling events within the female category after one year of GAHT.Adjustments based on competition data would ensure fairness.Further analysis after an additional 12 months is recommended to assess the impact of 2 years of GAHT.An outright ineligibility for the female category for transgender women athletes would hinder a true assessment of performance fairness.展开更多
This paper introduces a deep learning workflow to predict phase distributions within complex geometries during two-phase capillary-dominated drainage.We utilize subsamples from Computerized Tomography(CT)images of roc...This paper introduces a deep learning workflow to predict phase distributions within complex geometries during two-phase capillary-dominated drainage.We utilize subsamples from Computerized Tomography(CT)images of rocks and incorporate pixel size,interfacial tension,contact angle,and pressure as inputs.First,an efficient morphology-based simulator creates a diverse dataset of phase distributions.Then,two commonly used convolutional and recurrent neural networks are explored and their deficiencies are highlighted,particularly in capturing phase connectivity.Subsequently,we develop a Higher-Dimensional Vision Transformer(HD-ViT)that drains pores solely based on their size,with phase connectivity enforced as a post-processing step.This enables inference for images of varying sizes,resolutions,and inlet-outlet setup.After training on a massive dataset of over 9.5 million instances,HD-ViT achieves excellent performance.We demonstrate the accuracy and speed advantage of the model on new and larger sandstone and carbonate images.We further evaluate HD-ViT against experimental fluid distribution images and the corresponding Lattice-Boltzmann simulations,producing similar outcomes in a matter of seconds.In the end,we train and validate a 3D version of the model.展开更多
Elucidating the inherent origins of the sluggish hydrogen evolution reaction(HER)kinetics in alkaline media and developing high-performance electrocatalysts are fundamental for the advances of conventional alkaline wa...Elucidating the inherent origins of the sluggish hydrogen evolution reaction(HER)kinetics in alkaline media and developing high-performance electrocatalysts are fundamental for the advances of conventional alkaline water electrolyzers and emerging anion exchange membrane(AEM)electrolyzers.Here we present a facile electrochemical modification strategy for the synthesis of bi-component Co–Mo_((18%))/A-Co(OH)_(2)catalyst toward efficient HER catalysis in alkaline media.Porous Co–Mo alloys with adjustable Mo/Co atomic ratio are first prepared by H2-assisted cathodic electrodeposition.By virtue of the appropriate electronic structure and hydrogen binding energy,Co–Mo_((18%))is the most HER active among the alloys and is further activated by a constant-current electrochemical modification process.Physical characterizations reveal the formation of amorphous Co(OH)_(2)nanoparticles on the surface.Electrokinetic analysis combined with theoretical calculations reveal that the in-situ formed Co(OH)_(2)can efficiently promote the water dissociation,resulting in accelerated Volmer-step kinetics.As a result,the Co–Mo_((18%))/A-Co(OH)_(2)simultaneously achieves the optimization of the two factors dominating alkaline HER activity,i.e.,water dissociation and hydrogen adsorption/desorption via the bifunctional synergy of the bi-components.The high HER activity(η10 of 47 mV at 10 mA cm^(-2))of Co–Mo_((18%))/A-Co(OH)_(2)is close to benchmark Pt/C catalyst and comparable or superior to the most active non-noble metal catalysts.展开更多
Solid waste recycling is an economically sound strategy for preserving the environment,safeguarding natural resources,and diminishing the reliance on raw material consumption.Geopolymer technology offers a significant...Solid waste recycling is an economically sound strategy for preserving the environment,safeguarding natural resources,and diminishing the reliance on raw material consumption.Geopolymer technology offers a significant advantage by enabling the reuse and recycling of diverse materials.This research assesses how including silica fume and glass powder enhances the impact resistance of ultra-high-performance geopolymer concrete(UHPGC).In total,18 distinct mixtures were formulated by substituting ground granulated blast furnace slag with varying proportions of silica fume and glass powder,ranging from 10%to 40%.Similarly,for each of the mixtures above,steel fibre was added at a dosage of 1.5%to address the inherent brittleness of UHPGC.The mixtures were activated by combining sodium hydroxide and sodium silicate solution to generate geopolymer binders.The specimens were subjected to drop-weight impact testing,wherein an examination was carried out to evaluate various parameters,including flowability,density at fresh and hardened state,compressive strength,impact numbers indicative of cracking and failure occurrences,ductility index,and analysis of failure modes.Additionally,the variations in the impact test outcomes were analyzed using the Weibull distribution,and the findings corresponding to survival probability were offered.Furthermore,the microstructure of UHPGC was scrutinized through scanning electron microscopy.Findings reveal that the specimens incorporating glass powder exhibited lower cracking impact number values than those utilizing silica fume,with reductions ranging from 18.63%to 34.31%.Similarly,failure impact number values decreased from 8.26%to 28.46%across glass powder contents.The maximum compressive and impact strength was recorded in UHPGC,comprising 10%silica fume with fibres.展开更多
The aim of this study is to identify the influence of the dip angle of a pre-existing macrocrack on the lifetime and ultimate deformation of rock-like material. Prediction of lifetime has been studied for three groups...The aim of this study is to identify the influence of the dip angle of a pre-existing macrocrack on the lifetime and ultimate deformation of rock-like material. Prediction of lifetime has been studied for three groups of specimens under axial static compressive load levels. The specimens were investigated from 65% to 85% of UCS(uniaxial compressive strength) at an interval of 10% of UCS for the groups of specimens with a single modelled open flaw with a dip angle to the loading direction of 30°(first group), at an interval of 5% of UCS increment for the groups of specimens with single(second group), and double sequential open flaws with a dip angle to the loading direction of 60°(third group). This study shows that crack propagation in specimens with a single flaw follows the same sequences. At first, wing cracks appear, and then shear crack develops from the existing wing cracks. Shear cracking is responsible for specimen failure in all three groups. A slip is expected in specimens from the third group which connects two individual modelled open flaws. The moment of the slip is noticed as a characteristic rise in the axial deformation at a constant load level. It is also observed that axial deformation versus time follows the same pattern, irrespective of local geometry. Specimens from the first group exhibit higher axial deformation under different load levels in comparison with the specimens from the second and third groups.展开更多
In recent years,inverted perovskite solar cells(IPSCs)have attracted significant attention due to their low-temperature and cost-effective fabrication processes,hysteresis-free properties,excellent stability,and wide ...In recent years,inverted perovskite solar cells(IPSCs)have attracted significant attention due to their low-temperature and cost-effective fabrication processes,hysteresis-free properties,excellent stability,and wide application.The efficiency gap between IPSCs and regular structures has shrunk to less than 1%.Over the past few years,IPSC research has mainly focused on optimizing power conversion efficiency to accelerate the development of IPSCs.This review provides an overview of recent improvements in the efficiency of IPSCs,including interface engineering and novel film production techniques to overcome critical obstacles.Tandem and integrated applications of IPSCs are also summarized.Furthermore,prospects for further development of IPSCs are discussed,including the development of new materials,methods,and device structures for novel IPSCs to meet the requirements of commercialization.展开更多
During the production of palm oil,a significant amount of waste is generated.However,because of inefficient handling and utilization,these wastes are becoming a larger issue.As a result,one initiative is to use these ...During the production of palm oil,a significant amount of waste is generated.However,because of inefficient handling and utilization,these wastes are becoming a larger issue.As a result,one initiative is to use these wastes in the pavement industry as sustainable materials.However,there is still a lack of understanding about the wider incorporation of palm oil waste in asphalt pavement and its performance.This study examines existing literature on the use of various wastes in the pavement industry,including palm oil clinker(POC),palm oil fibre(POF),palm kernel shell(PKS),and palm oil fuel ash(POFA).As a result,this paper presents a systematic review and scientometric investigation of related study publications on many uses of palm oil waste in the asphalt pavement industry and its performance from 2009 to 2022.The VOS viewer application was used to conduct the sciento-metric study analysis.The relationship between interactions detected in co-authored country studies cited sources of co-citation,and the keyword of the co-occurrence and publication source enabled the identification of the research gap.According to the systematic literature review,40%–60% POC can be used to fine aggregate for optimal performance,while 0–100%PKS can be used to replace coarse aggregate.In addition,50%–80% POFA or POC fine(POCF)can be used as a filler replacement,5%–8% POCF or POFA as a bitumen modifier,and 0.3% POF as a stabilizing additive.Furthermore,the study demonstrates that the safety of utilizing wastes with more than 50% CO_(2) emissions can be curtailed with minimal heavy metal leaching and radioactivity levels.The scientometric analysis may encourage researchers to seek out gaps in the literature that will aid in the long-term,multifaceted use of palm oil wastes in the asphalt pavement industry.Furthermore,the study recommends employing and researching the enormous potential of using palm oil waste in the pavement sectors because they are more sustainable and have better performance.However,there are some barriers to展开更多
Safe disposal of high-level radioactive nuclear waste(HLW)is crucial for human health and the environment,as well as for sustainable development.Deep geological disposal in sparsely fractured crystalline rock is consi...Safe disposal of high-level radioactive nuclear waste(HLW)is crucial for human health and the environment,as well as for sustainable development.Deep geological disposal in sparsely fractured crystalline rock is considered one of the most favorable methods for final disposal of HLW.Extensive research has been conducted worldwide and many countries have initiated their own national development programs for deep geological disposal.Significant advancements of national programs for deep geological disposal of HLW in crystalline rock have been achieved in Sweden and Finland,which are currently under site development stage,focusing on detailed site characterization,repository construction,and post-closure safety analysis.Continued research and development remain important in the site development stage to ensure long-term safety of the HLW disposal repository.This work presents an overview and discussion of the progress as well as remaining open scientific issues and possibilities related to site development for safe disposal of HLW in crystalline rock.We emphasize that developing a comprehensive and convergent understanding of the coupled thermal,hydraulic,mechanical,chemical and biological(THMCB)processes in fractured crystalline rock remains the most important yet challenging topic for future studies towards safe disposal of HLW in crystalline rock.Advancements in laboratory facilities/techniques and computational models,as well as available comprehensive field data from site developments,provide new opportunities to enhance our understanding of the coupled processes and thereby repository design for safe geological disposal of HLW in crystalline rock.展开更多
The central aim of this paper is to address the role of unconformities in affecting reservoir quality.Do they facilitate diagenesis that leads to either enhanced or reduced porosity through dissolution or cementation?...The central aim of this paper is to address the role of unconformities in affecting reservoir quality.Do they facilitate diagenesis that leads to either enhanced or reduced porosity through dissolution or cementation?Or,do they have little effect?We have investigated the Late Triassic Skagerrak sandstone reservoir underlying the Mid-Cimmerian Unconformity in the Kittiwake Field,central North Sea.There is strong evidence for the development of secondary porosity through the dissolution of unstable silicate minerals,primarily feldspars.This includes the presence of oversized pores,partial dissolution of framework grains,and complete dissolution of grains leaving remnant grain margins and partially filled cores.This dissolution as a late-stage event is demonstrated by the complete lack of compaction effects on the secondary pores and diagenetic products despite present burial depths in excess of 3000 m.These observations,coupled with an absence of systematic trends linked to the unconformity surface in respects of reservoir porosity,feldspar amount and dissolution,and kaolinization,lead to the conclusion that there has been no effect of the Mid-Cimmerian Unconformity on reservoir quality in the Kittiwake Field.There is no evidence for leaching or cementation linked to meteoric water influx either shortly after deposition or following the uplift and exposure,which led to development of the Mid-Cimmerian Unconformity.Instead,we propose that the late-stage dissolution of feldspar and generation of secondary porosity are most likely related to the influx of organic acids and carbon dioxide generated either from thermogenic maturation of the source rock or from biodegradation of oil within the reservoir near the oil-water contact(OWC)transition zone.展开更多
A spillway aerator should guarantee favorable flow conditions in the coupled water-air system even if the aerator is unconventionally wide. Eight air-vent configurations are devised and incorporated into a 35-m wide c...A spillway aerator should guarantee favorable flow conditions in the coupled water-air system even if the aerator is unconventionally wide. Eight air-vent configurations are devised and incorporated into a 35-m wide chute aerator for a generalized study. Computational fluid dynamics(CFD) simulations are performed to explore their effects on water-jet and air-cavity features. The Re-normalisation group(RNG) k-ε turbulence model and the two-fluid model are combined to predict the two-phase flow field. The results demonstrate appreciable influences of the vent layouts on the water-air flow. The air vents stir the air motion and re-distribute the cavity air pressure. Once the vent layout is modified, reciprocal adjustments exist between the jet behavior and air-pressure field in the cavity, thus leading to considerable differences in air-flow rate, jet-trajectory length, vent air-flow distribution across the chute, etc. The large width plays a discernable role in affecting the aerated flow. Telling differences exist between the near-wall region and the central part of the chute. To improve the duct pressure propagation, a gradual augment of the vent area should be assigned towards the chute center. Relative to single-slot vents across the flow, the layouts with segregated vents gain by comparison. A designer should see to it that a vented aerator operates satisfactorily for a given range of flow discharges.展开更多
The diffusivity equation is a partial differential equation(PDE)which can be used for fluid flow modeling in porous media.Determining reservoir parameters from pressure data(i.e.,pressure transient analysis)is one of ...The diffusivity equation is a partial differential equation(PDE)which can be used for fluid flow modeling in porous media.Determining reservoir parameters from pressure data(i.e.,pressure transient analysis)is one of the most important steps in the process of field development.This initial evaluation can be used to make decisions about future developments.Wireline Formation Testing(WFT)is one of the most popular techniques for parameter estimation and has received significant attention in recent years.The main problem plaguing WFT is a phenomenon known as the“supercharging effect,”which essentially refers to mud invasion,and this,in turn,alters pressure distribution across the system.In this study,an analytical solution for fluid flow modeling in spherical coordinates with non-uniform initial pressure is presented.This new procedure takes into account the effect of mud invasion,or,in other words,the supercharging effect.The accuracy of this derivation was validated using previous semianalytical solutions(the Laplace method)in addition to field data.New type curves and dimensionless parameters,which can be used for pressure transient analysis,are also proposed.This procedure is applied to the WFT data that was obtained from an oil field in the south of Iran,and an excellent agreement(less than 10%error)was observed.In addition,there is considerable uncertainty regarding the radius of investigation for spherical flow.This is important as this parameter greatly affects the applicability of WFT.The analytical derivation of this study was used to determine a reasonable value for this parameter as well.展开更多
This paper explored the antecedents and the role of local artisans in Spatial Planning (SP) activities in Ghana. The paper was based on the results of an inspection of 5896 already built houses at Mepe in the Volta Re...This paper explored the antecedents and the role of local artisans in Spatial Planning (SP) activities in Ghana. The paper was based on the results of an inspection of 5896 already built houses at Mepe in the Volta Region of Ghana. A mixed method research approach was used to gather the data through snowball non-probability sampling technique. It enabled the researchers to identify 100 local artisans. Survey questionnaires were used, which was followed by structured interviews with five (5) elders who lived in the town for over 65 years. The results showed that the early houses were built on community lands with mud and thatch clustered with narrow and unnamed alleys. Property owners heavily depended on local artisans for professional guidance, although some artisans were ill-trained and unaware of existing government SP regulations. The study was limited to artisans who practiced at the local community level. The findings showed that many local artisans were poorly trained, resulting in poor workmanship and non-compliance with local planning regulations. The paper recommends the integration of SP into the artisanal curricula at both local and national levels to improve their skills.展开更多
Central air-conditioning systems predominantly operate under partial load conditions.The optimization of a differential pressure setpoint in the chilled water system of a central air-conditioning system leads to a mor...Central air-conditioning systems predominantly operate under partial load conditions.The optimization of a differential pressure setpoint in the chilled water system of a central air-conditioning system leads to a more energy-efficient operation.Determining the differential pressure adjustment value based on the terminal user's real-time demand is one of the critical issues to be addressed during the optimal control process.Furthermore,the online application of the differential pressure setpoint optimization method needs to be considered,along with the stability of the system.This paper proposes a variable differential pressure reset method with an adaptive adjustment algorithm based on the Mamdani fuzzy model.The proposed method was compared with differential pressure reset methods with reference to the chilled water differential temperature,outdoor temperature,and linear model based on the adjustment algorithm.The energy-saving potential,temperature control effect,and avoidance of the most unfavorable thermodynamic loop effects of the four methods were investigated experimentally.The results indicated that,while satisfying the terminal user's energy supply demand and ensuring the avoidance of the most unfavorable thermodynamic loop,the proposed adaptive adjustment algorithm also decreased the differential pressure setpoint value by 25.1%—59.1%and achieved energy savings of 10.6%-45.0%.By monitoring the valve position and supply air temperature of each terminal user,the proposed method exhibited suitable online adaptability and could be flexibly applied to buildings with random load changes.展开更多
基金This work was supported by the Global Frontier R&D Programme(2013M3A6B1078875)of the Center for Hybrid Interface Materials(HIM)funded by the Ministry of Science,ICT&Future Planningby the Human Resources Development program(No.20184010201720)of a Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Ministry of Trade,Industry,and Energy of the Korean government.
文摘As electric vehicle(EV)sales grew approximately 50%year-over-year,surpassing 3.2 million units in 2020,the“roaring era”of EV is around the corner.To meet the increasing demand for low cost and high energy density batteries,anode-free configuration,with no heavy and voluminous host material on the current collector,has been proposed and further investigated.Nevertheless,it always suffers from several non-negligible“bottlenecks”,such as fragile solid electrolyte interface,deteriorated cycling reversibility,and uncontrolled dendrite formation.Inspired by the“compensatory effect”of some disabled people with other specific functions strengthened to make up for their inconvenience,corresponding quasi-compensatory measures after anode removal,involving dimensional compensation,SEI robustness compensation,lithio-philicity compensation,and lithium source compensation,have been carried out and achieved significant battery performance enhancement.In this review,the chemistry,challenges,and rationally designed“quasi-compensatory effect”associated with anode-free lithium-ion battery are systematically discussed with several possible R&D directions that may aid,direct,or facilitate future research on lithium storage in anode-free configuration essentially emphasized.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.U22A20166,51904190,12172230 and U19A2098)the Department of Science and Technology of Guangdong Province(No.2019ZT08G315)。
文摘The presence of sealed or semi-sealed,multiscale natural fracture systems appears to be crucial for the successful stimulation of deep reservoirs.To explore the reaction of such systems to reservoir stimulation,a new numerical simulation approach for hydraulic stimulation has been developed,trying to establish a realistic model of the physics involved.Our new model successfully reproduces dynamic fracture activation,network generation,and overall reservoir permeability enhancement.Its outputs indicate that natural fractures facilitate stimulation far beyond the near-wellbore area,and can significantly improve the hydraulic conductivity of unconventional geo-energy reservoirs.According to our model,the fracture activation patterns are jointly determined by the occurrence of natural fractures and the in situ stress.High-density natural fractures,high-fluid pressure,and low effective stress environments promote the formation of complex fracture networks during stimulation.Multistage or multicluster fracturing treatments with an appropriate spacing also increase the stimulated reservoir area(SRA).The simulation scheme demonstrated in this work offers the possibility to elucidate the complex multiphysical couplings seen in the field through detailed site-specific modeling.
文摘The discovery of chirped pulse amplification has led to great improvements in laser technology,enabling energetic laser beams to be compressed to pulse durations of tens of femtoseconds and focused to a few micrometers.Protons with energies of tens of MeV can be accelerated using,for instance,target normal sheath acceleration and focused on secondary targets.Under such conditions,nuclear reactions can occur,with the production of radioisotopes suitable for medical application.The use of high-repetition lasers to produce such isotopes is competitive with conventional methods mostly based on accelerators.In this paper,we study the production of^(67)Cu,^(63)Zn,^(18)F,and^(11)C,which are currently used in positron emission tomography and other applications.At the same time,we study the reactions^(10)B(p,α)^(7)Be and^(70)Zn(p,4n)^(67)Ga to put further constraints on the proton distributions at different angles,as well as the reaction^(11)B(p,α)^(8)Be relevant for energy production.The experiment was performed at the 1 PW laser facility at VegaⅢin Salamanca,Spain.Angular distributions of radioisotopes in the forward(with respect to the laser direction)and backward directions were measured using a high purity germanium detector.Our results are in reasonable agreement with numerical estimates obtained following the approach of Kimura and Bonasera[Nucl.Instrum.Methods Phys.Res.,Sect.A 637,164–170(2011)].
基金supported by the National Natural Science Foundation of China(72022004,52370189,and 52200228)National Key Research and Development Program Project(2021YFC3200205).
文摘Recent phenomena such as pandemics,geopolitical tensions,and climate change-induced extreme weather events have caused transportation network interruptions,revealing vulnerabilities in the global supply chain.A salient example is the March 2021 Suez Canal blockage,which delayed 432 vessels carrying cargo valued at$92.7 billion,triggering widespread supply chain disruptions.Our ability to model the spatiotemporal ramifications of such incidents remains limited.To fill this gap,we develop an agent-based complex network model integrated with frequently updated maritime data.The Suez Canal blockage is taken as a case study.The results indicate that the effects of such blockages go beyond the directly affected countries and sectors.The Suez Canal blockage led to global losses of about$136.9($127.5–$147.3)billion,with India suffering 75%of these losses.Global losses show a nonlinear relationship with the duration of blockage and exhibit intricate trends post blockage.Our proposed model can be applied to diverse blockage scenarios,potentially acting as an earlyalert system for the ensuing supply chain impacts.Furthermore,high-resolution daily data post blockage offer valuable insights that can help nations and industries enhance their resilience against similar future events.
基金supported by the National Natural Science Foundation of China (Grant No.52,078,096)the Fundamental Research Funds for the Central Universities (Grant No.DUT20JC47)the open Foun-dation of the Key lab of Anhui Province Key Laboratory of Intelligent Building&Building Energy Saving (Grant No.IBES2021KF03).
文摘Variable air volume air-conditioning system(VAV system)has multiple control loops that interfered with each other,which has serious impacts on its actual operation effect.To solve this problem,the index of global hydraulic stability,which takes the physical quantity of the pipe network pressure and the air flow rate as reference,is proposed based on Graph theory,and a pipe network model for the hydraulic calculation is built.Then,the simulation study based on the actual operation data is carried out in MATLAB.The distribution of the pressure and the air flow in the pipe network is obtained,and the action interferences among adjacent terminal boxes are analyzed based on global hydraulic stability under damper position regulation strategy(DP strategy)and fan frequency regulation strategy(FF strategy).Results indicate that the FF strategy can decrease the total change distance of the damper position compared with the DP strategy,and then the fluctuation of the pressure and the air flow can be reduced.The contribution of this study is to provide an evaluation index of global hydraulic stability,which can also be used in other air-conditioning systems with multiple terminals and multiple control loops.
文摘In the last forty years,the rise of HIV has undoubtedly become a major concern in the field of public health,imposing significant economic burdens on affected regions.Consequently,it becomes imperative to undertake comprehensive investigations into the mechanisms governing the dissemination of HIV within the human body.In this work,we have devised a mathematical model that elucidates the intricate interplay between CD4^(+)T-cells and viruses of HIV,employing the principles of fractional calculus.The production rate of CD4^(+)T-cells,like other immune cells depends on certain factors such as age,health status,and the presence of infections or diseases.Therefore,we incorporate a variable source term in the dynamics of HIV infection with a saturated incidence rate to enhance the precision of our findings.We introduce the fundamental concepts of fractional operators as a means of scrutinizing the proposed HIV model.To facilitate a deeper understanding of our system,we present an iterative scheme that elucidates the trajectories of the solution pathways of the system.We show the time series analysis of our model through numerical findings to conceptualize and understand the key factors of the system.In addition to this,we present the phase portrait and the oscillatory behavior of the system with the variation of different input parameters.This information can be utilized to predict the long-term behavior of the system,including whether it will converge to a steady state or exhibit periodic or chaotic oscillations.
基金supported by the National Natural Science Foundation of China(Grant No.52078096)the Natural Science Foundation Joint Fund of Liaoning Province(Grant No.2023-MSBA-023)+1 种基金2023 Dalian University of Technology-Cardiff University Cooperation and Exchange Foundation Project,2023 International Exchange Foundation Project of“Co-Creation of Excellence Program”from Dalian University of Technology(Grant No.DUTIO-ZG-202307)the Key Project of DUT for International Students Studying and Researching in China:Innovation and Practice of Talent Cultivation Model in the Field of Smart Buildings for the“Belt and Road"Initiative(Grant No.1103-82120001).
文摘Building air conditioning systems(ACs)can contribute to the stable operation of power grids by participating in peak load shaving programs,but the participants need a fast and accurate zone temperature prediction model,e.g.,the detailed room thermal-resistance(RC)model,to improve peak shaving effect and avoid obvious thermal discomfort.However,when applying the detailed room RC model to multi-zone buildings,conventional studies mostly consider the heat transfer among neighboring rooms,which contributes little to the prediction accuracy improvement,but leads to complicated model structure and heavy computation.Thus,a distributed RC model is developed for multi-zone buildings in this study.Compared to conventional models,the proposed model considers the total heat transfer between the building and the air,and ignores the heat transfer among indoor air in neighboring rooms through internal walls with heavy thermal mass,thereby having comparable temperature prediction accuracy,simpler structure,and stronger robustness.Based on the model,the effectiveness of passive pre-cooling strategies in reducing the air conditioning loads during peak periods is investigated.Results indicate that the thermal insulation performance of opaque building envelope is quite important to the flexibility enhancement of air conditioning loads.With an uninsulated building envelope,passive pre-cooling is useless for the peak load shaving.In comparison,well insulated opaque building envelope enables the building thermal mass to be utilized through passive pre-cooling,which leads to the air conditioning loads during peak periods being further reduced by about 12%.
文摘Background and Aims:The Union Cycliste Internationale has deemed transgender female athlete’s ineligible for the female category due to concerns about performance advantages.We conducted a follow-up analysis on laboratorybased performance indicators of sports performance using data from a longitudinally assessed transgender woman athlete undergoing gender-affrming hormone therapy(GAHT).Methods:We evaluated laboratory performance indicators in transgender and cisgender women athletes using dualenergy X-ray absorptiometry scanning,handgrip strength measurement,jump testing,and cardiopulmonary exercise.Additionally,we assessed a transgender sub-elite cyclist before and after undergoing GAHT.Results:After one year of GAHT,the transgender athlete showed declines in handgrip strength(7–13%),countermovement jump(23–29%),and V̇O_(2)max(15–30%).After 3 months,several performance indicators(absolute handgrip,peak power,relative peak power,average power,relative average power,V̇O2max and relative V̇O_(2)max)were above the mean of cisgender female athletes,while others(Relative handgrip,countermovement jump and relative countermovement jump)were below.Similar trends were observed at 6 months and 1 year.Summary:This hypothetical analysis,although with limited evidence,suggests the transgender athlete could compete equitably in elite cycling events within the female category after one year of GAHT.Adjustments based on competition data would ensure fairness.Further analysis after an additional 12 months is recommended to assess the impact of 2 years of GAHT.An outright ineligibility for the female category for transgender women athletes would hinder a true assessment of performance fairness.
基金supported by the International Cooperation Programme of Chengdu City(No.2020-GH02-00023-HZ)。
文摘This paper introduces a deep learning workflow to predict phase distributions within complex geometries during two-phase capillary-dominated drainage.We utilize subsamples from Computerized Tomography(CT)images of rocks and incorporate pixel size,interfacial tension,contact angle,and pressure as inputs.First,an efficient morphology-based simulator creates a diverse dataset of phase distributions.Then,two commonly used convolutional and recurrent neural networks are explored and their deficiencies are highlighted,particularly in capturing phase connectivity.Subsequently,we develop a Higher-Dimensional Vision Transformer(HD-ViT)that drains pores solely based on their size,with phase connectivity enforced as a post-processing step.This enables inference for images of varying sizes,resolutions,and inlet-outlet setup.After training on a massive dataset of over 9.5 million instances,HD-ViT achieves excellent performance.We demonstrate the accuracy and speed advantage of the model on new and larger sandstone and carbonate images.We further evaluate HD-ViT against experimental fluid distribution images and the corresponding Lattice-Boltzmann simulations,producing similar outcomes in a matter of seconds.In the end,we train and validate a 3D version of the model.
基金supported by the National Natural Science Foundation of China(No.51771037)Low Carbon Energy Research Funding Initiative(No.SC22/22-71151E).
文摘Elucidating the inherent origins of the sluggish hydrogen evolution reaction(HER)kinetics in alkaline media and developing high-performance electrocatalysts are fundamental for the advances of conventional alkaline water electrolyzers and emerging anion exchange membrane(AEM)electrolyzers.Here we present a facile electrochemical modification strategy for the synthesis of bi-component Co–Mo_((18%))/A-Co(OH)_(2)catalyst toward efficient HER catalysis in alkaline media.Porous Co–Mo alloys with adjustable Mo/Co atomic ratio are first prepared by H2-assisted cathodic electrodeposition.By virtue of the appropriate electronic structure and hydrogen binding energy,Co–Mo_((18%))is the most HER active among the alloys and is further activated by a constant-current electrochemical modification process.Physical characterizations reveal the formation of amorphous Co(OH)_(2)nanoparticles on the surface.Electrokinetic analysis combined with theoretical calculations reveal that the in-situ formed Co(OH)_(2)can efficiently promote the water dissociation,resulting in accelerated Volmer-step kinetics.As a result,the Co–Mo_((18%))/A-Co(OH)_(2)simultaneously achieves the optimization of the two factors dominating alkaline HER activity,i.e.,water dissociation and hydrogen adsorption/desorption via the bifunctional synergy of the bi-components.The high HER activity(η10 of 47 mV at 10 mA cm^(-2))of Co–Mo_((18%))/A-Co(OH)_(2)is close to benchmark Pt/C catalyst and comparable or superior to the most active non-noble metal catalysts.
基金SASTRA Deemed University,India for its generous research support。
文摘Solid waste recycling is an economically sound strategy for preserving the environment,safeguarding natural resources,and diminishing the reliance on raw material consumption.Geopolymer technology offers a significant advantage by enabling the reuse and recycling of diverse materials.This research assesses how including silica fume and glass powder enhances the impact resistance of ultra-high-performance geopolymer concrete(UHPGC).In total,18 distinct mixtures were formulated by substituting ground granulated blast furnace slag with varying proportions of silica fume and glass powder,ranging from 10%to 40%.Similarly,for each of the mixtures above,steel fibre was added at a dosage of 1.5%to address the inherent brittleness of UHPGC.The mixtures were activated by combining sodium hydroxide and sodium silicate solution to generate geopolymer binders.The specimens were subjected to drop-weight impact testing,wherein an examination was carried out to evaluate various parameters,including flowability,density at fresh and hardened state,compressive strength,impact numbers indicative of cracking and failure occurrences,ductility index,and analysis of failure modes.Additionally,the variations in the impact test outcomes were analyzed using the Weibull distribution,and the findings corresponding to survival probability were offered.Furthermore,the microstructure of UHPGC was scrutinized through scanning electron microscopy.Findings reveal that the specimens incorporating glass powder exhibited lower cracking impact number values than those utilizing silica fume,with reductions ranging from 18.63%to 34.31%.Similarly,failure impact number values decreased from 8.26%to 28.46%across glass powder contents.The maximum compressive and impact strength was recorded in UHPGC,comprising 10%silica fume with fibres.
文摘The aim of this study is to identify the influence of the dip angle of a pre-existing macrocrack on the lifetime and ultimate deformation of rock-like material. Prediction of lifetime has been studied for three groups of specimens under axial static compressive load levels. The specimens were investigated from 65% to 85% of UCS(uniaxial compressive strength) at an interval of 10% of UCS for the groups of specimens with a single modelled open flaw with a dip angle to the loading direction of 30°(first group), at an interval of 5% of UCS increment for the groups of specimens with single(second group), and double sequential open flaws with a dip angle to the loading direction of 60°(third group). This study shows that crack propagation in specimens with a single flaw follows the same sequences. At first, wing cracks appear, and then shear crack develops from the existing wing cracks. Shear cracking is responsible for specimen failure in all three groups. A slip is expected in specimens from the third group which connects two individual modelled open flaws. The moment of the slip is noticed as a characteristic rise in the axial deformation at a constant load level. It is also observed that axial deformation versus time follows the same pattern, irrespective of local geometry. Specimens from the first group exhibit higher axial deformation under different load levels in comparison with the specimens from the second and third groups.
基金the Research Grants Council of Hong Kong(GRF Grant Nos.15221320,CRF C7018-20G)the Shenzhen Science and Technology Innovation Commission(Project No.JCYJ 20200109105003940,SGDX20201103095403016)+6 种基金the Hong Kong Innovation and Technology Commission(GHP/205/20SZ)the Sir Sze-yuen Chung Endowed Professorship Fund(8-8480)provided by the Hong Kong Polytechnic Universitythe GuangdongHong Kong-Macao Joint Laboratory for Photonic-Thermal-Electrical Energy Materials and Devices(GDSTC No.2019B121205001)the National Natural Science Foundation of China(Grant No.91963129)the Guangdong Provincial Key Laboratory of Energy Materials for Electric Power(Grant No.2018B030322001)the Student Innovation Training Program(Grant Nos.2021S07)from Southern University of Science and Technology(SUSTech)the Special Funds for the Cultivation of Guangdong College Students’Scientific and Technological Innovation(pdjh2022c0003&pdjh2022c0005)。
文摘In recent years,inverted perovskite solar cells(IPSCs)have attracted significant attention due to their low-temperature and cost-effective fabrication processes,hysteresis-free properties,excellent stability,and wide application.The efficiency gap between IPSCs and regular structures has shrunk to less than 1%.Over the past few years,IPSC research has mainly focused on optimizing power conversion efficiency to accelerate the development of IPSCs.This review provides an overview of recent improvements in the efficiency of IPSCs,including interface engineering and novel film production techniques to overcome critical obstacles.Tandem and integrated applications of IPSCs are also summarized.Furthermore,prospects for further development of IPSCs are discussed,including the development of new materials,methods,and device structures for novel IPSCs to meet the requirements of commercialization.
文摘During the production of palm oil,a significant amount of waste is generated.However,because of inefficient handling and utilization,these wastes are becoming a larger issue.As a result,one initiative is to use these wastes in the pavement industry as sustainable materials.However,there is still a lack of understanding about the wider incorporation of palm oil waste in asphalt pavement and its performance.This study examines existing literature on the use of various wastes in the pavement industry,including palm oil clinker(POC),palm oil fibre(POF),palm kernel shell(PKS),and palm oil fuel ash(POFA).As a result,this paper presents a systematic review and scientometric investigation of related study publications on many uses of palm oil waste in the asphalt pavement industry and its performance from 2009 to 2022.The VOS viewer application was used to conduct the sciento-metric study analysis.The relationship between interactions detected in co-authored country studies cited sources of co-citation,and the keyword of the co-occurrence and publication source enabled the identification of the research gap.According to the systematic literature review,40%–60% POC can be used to fine aggregate for optimal performance,while 0–100%PKS can be used to replace coarse aggregate.In addition,50%–80% POFA or POC fine(POCF)can be used as a filler replacement,5%–8% POCF or POFA as a bitumen modifier,and 0.3% POF as a stabilizing additive.Furthermore,the study demonstrates that the safety of utilizing wastes with more than 50% CO_(2) emissions can be curtailed with minimal heavy metal leaching and radioactivity levels.The scientometric analysis may encourage researchers to seek out gaps in the literature that will aid in the long-term,multifaceted use of palm oil wastes in the asphalt pavement industry.Furthermore,the study recommends employing and researching the enormous potential of using palm oil waste in the pavement sectors because they are more sustainable and have better performance.However,there are some barriers to
文摘Safe disposal of high-level radioactive nuclear waste(HLW)is crucial for human health and the environment,as well as for sustainable development.Deep geological disposal in sparsely fractured crystalline rock is considered one of the most favorable methods for final disposal of HLW.Extensive research has been conducted worldwide and many countries have initiated their own national development programs for deep geological disposal.Significant advancements of national programs for deep geological disposal of HLW in crystalline rock have been achieved in Sweden and Finland,which are currently under site development stage,focusing on detailed site characterization,repository construction,and post-closure safety analysis.Continued research and development remain important in the site development stage to ensure long-term safety of the HLW disposal repository.This work presents an overview and discussion of the progress as well as remaining open scientific issues and possibilities related to site development for safe disposal of HLW in crystalline rock.We emphasize that developing a comprehensive and convergent understanding of the coupled thermal,hydraulic,mechanical,chemical and biological(THMCB)processes in fractured crystalline rock remains the most important yet challenging topic for future studies towards safe disposal of HLW in crystalline rock.Advancements in laboratory facilities/techniques and computational models,as well as available comprehensive field data from site developments,provide new opportunities to enhance our understanding of the coupled processes and thereby repository design for safe geological disposal of HLW in crystalline rock.
文摘The central aim of this paper is to address the role of unconformities in affecting reservoir quality.Do they facilitate diagenesis that leads to either enhanced or reduced porosity through dissolution or cementation?Or,do they have little effect?We have investigated the Late Triassic Skagerrak sandstone reservoir underlying the Mid-Cimmerian Unconformity in the Kittiwake Field,central North Sea.There is strong evidence for the development of secondary porosity through the dissolution of unstable silicate minerals,primarily feldspars.This includes the presence of oversized pores,partial dissolution of framework grains,and complete dissolution of grains leaving remnant grain margins and partially filled cores.This dissolution as a late-stage event is demonstrated by the complete lack of compaction effects on the secondary pores and diagenetic products despite present burial depths in excess of 3000 m.These observations,coupled with an absence of systematic trends linked to the unconformity surface in respects of reservoir porosity,feldspar amount and dissolution,and kaolinization,lead to the conclusion that there has been no effect of the Mid-Cimmerian Unconformity on reservoir quality in the Kittiwake Field.There is no evidence for leaching or cementation linked to meteoric water influx either shortly after deposition or following the uplift and exposure,which led to development of the Mid-Cimmerian Unconformity.Instead,we propose that the late-stage dissolution of feldspar and generation of secondary porosity are most likely related to the influx of organic acids and carbon dioxide generated either from thermogenic maturation of the source rock or from biodegradation of oil within the reservoir near the oil-water contact(OWC)transition zone.
基金part of research project "Hydraulic design of spillway aerators"funded in part by Swedish Hydropower Centre(SVC)+2 种基金Vattenfall R&DFortum GenerationUniper/Sweco have indirectly facilitated the study
文摘A spillway aerator should guarantee favorable flow conditions in the coupled water-air system even if the aerator is unconventionally wide. Eight air-vent configurations are devised and incorporated into a 35-m wide chute aerator for a generalized study. Computational fluid dynamics(CFD) simulations are performed to explore their effects on water-jet and air-cavity features. The Re-normalisation group(RNG) k-ε turbulence model and the two-fluid model are combined to predict the two-phase flow field. The results demonstrate appreciable influences of the vent layouts on the water-air flow. The air vents stir the air motion and re-distribute the cavity air pressure. Once the vent layout is modified, reciprocal adjustments exist between the jet behavior and air-pressure field in the cavity, thus leading to considerable differences in air-flow rate, jet-trajectory length, vent air-flow distribution across the chute, etc. The large width plays a discernable role in affecting the aerated flow. Telling differences exist between the near-wall region and the central part of the chute. To improve the duct pressure propagation, a gradual augment of the vent area should be assigned towards the chute center. Relative to single-slot vents across the flow, the layouts with segregated vents gain by comparison. A designer should see to it that a vented aerator operates satisfactorily for a given range of flow discharges.
文摘The diffusivity equation is a partial differential equation(PDE)which can be used for fluid flow modeling in porous media.Determining reservoir parameters from pressure data(i.e.,pressure transient analysis)is one of the most important steps in the process of field development.This initial evaluation can be used to make decisions about future developments.Wireline Formation Testing(WFT)is one of the most popular techniques for parameter estimation and has received significant attention in recent years.The main problem plaguing WFT is a phenomenon known as the“supercharging effect,”which essentially refers to mud invasion,and this,in turn,alters pressure distribution across the system.In this study,an analytical solution for fluid flow modeling in spherical coordinates with non-uniform initial pressure is presented.This new procedure takes into account the effect of mud invasion,or,in other words,the supercharging effect.The accuracy of this derivation was validated using previous semianalytical solutions(the Laplace method)in addition to field data.New type curves and dimensionless parameters,which can be used for pressure transient analysis,are also proposed.This procedure is applied to the WFT data that was obtained from an oil field in the south of Iran,and an excellent agreement(less than 10%error)was observed.In addition,there is considerable uncertainty regarding the radius of investigation for spherical flow.This is important as this parameter greatly affects the applicability of WFT.The analytical derivation of this study was used to determine a reasonable value for this parameter as well.
文摘This paper explored the antecedents and the role of local artisans in Spatial Planning (SP) activities in Ghana. The paper was based on the results of an inspection of 5896 already built houses at Mepe in the Volta Region of Ghana. A mixed method research approach was used to gather the data through snowball non-probability sampling technique. It enabled the researchers to identify 100 local artisans. Survey questionnaires were used, which was followed by structured interviews with five (5) elders who lived in the town for over 65 years. The results showed that the early houses were built on community lands with mud and thatch clustered with narrow and unnamed alleys. Property owners heavily depended on local artisans for professional guidance, although some artisans were ill-trained and unaware of existing government SP regulations. The study was limited to artisans who practiced at the local community level. The findings showed that many local artisans were poorly trained, resulting in poor workmanship and non-compliance with local planning regulations. The paper recommends the integration of SP into the artisanal curricula at both local and national levels to improve their skills.
基金support provided by the National Key Research and Development Project of China(No.2017YFC0704100,under the title New Generation Intelligent Building Platform Techniques)Liaoning Natural Science Foundation Guidance Plan(No.20180551057)+1 种基金Dalian High-level Talent Innovation Support Program(Youth Technology Star)(No.2017RQ099)Fundamental Research Funds for the Central Universities(No.DUT20JC47)。
文摘Central air-conditioning systems predominantly operate under partial load conditions.The optimization of a differential pressure setpoint in the chilled water system of a central air-conditioning system leads to a more energy-efficient operation.Determining the differential pressure adjustment value based on the terminal user's real-time demand is one of the critical issues to be addressed during the optimal control process.Furthermore,the online application of the differential pressure setpoint optimization method needs to be considered,along with the stability of the system.This paper proposes a variable differential pressure reset method with an adaptive adjustment algorithm based on the Mamdani fuzzy model.The proposed method was compared with differential pressure reset methods with reference to the chilled water differential temperature,outdoor temperature,and linear model based on the adjustment algorithm.The energy-saving potential,temperature control effect,and avoidance of the most unfavorable thermodynamic loop effects of the four methods were investigated experimentally.The results indicated that,while satisfying the terminal user's energy supply demand and ensuring the avoidance of the most unfavorable thermodynamic loop,the proposed adaptive adjustment algorithm also decreased the differential pressure setpoint value by 25.1%—59.1%and achieved energy savings of 10.6%-45.0%.By monitoring the valve position and supply air temperature of each terminal user,the proposed method exhibited suitable online adaptability and could be flexibly applied to buildings with random load changes.
