Mining activities in the Copperbelt province of Zambia have been of great environmental concern, despite recorded improvements in the socio-economic sector. Heavy metal contamination of soils resulting from depositing...Mining activities in the Copperbelt province of Zambia have been of great environmental concern, despite recorded improvements in the socio-economic sector. Heavy metal contamination of soils resulting from depositing mine tailings and rock waste has posed possible health risks for communities nearer such facilities. The current study was conducted around residential homes surrounding Kitwe slimes (TD25). This work investigated levels of Co, Cu, Fe, Mn and Pb in the soils, and avocado and lemons fruits, growing near TD25. Heavy metals were analyzed using Atomic Absorption Spectrophotometer. The work further assessed the estimated daily intake (EDI) associated with potential health risks to humans. In the soil, concentration levels of heavy metals showed a trend in the order: Fe > Cu > Mn > Co > Pb. Heavy metal contents in avocado and lemon fruits at 200 and 400 m away from TD25, all had p-values < 0.05. The distances from the suspect source (TD25) to where the fruit trees were grown, had no influence on their concentration in the fruit samples. Fruit sample results showed that Fe had the highest EDI of 0.22 mg·kg<sup>-1</sup> (avocado) and 0.14 mg·kg<sup>-1</sup> (lemon), though both results were far below the FAO/WHO standard range (12.5 - 19.6 mg·kg<sup>-1</sup>). For both fruits, Co and Pb results were negligible. The concentration of the five heavy metals in avocado and lemon fruits grown around Kitwe slimes did not pose any health risks to the consumers.展开更多
The minimum rolling thickness in asymmetrical rolling was analyzed compared with that in symmetrical rolling. The differential equilibrium equations on forces were established to calculate the asymmetrical rolling for...The minimum rolling thickness in asymmetrical rolling was analyzed compared with that in symmetrical rolling. The differential equilibrium equations on forces were established to calculate the asymmetrical rolling force equation by slab method. An implicit expression of the minimum rolling thickness was then derived from the rolling force equation and Hitehcock equation. The results show that permissible minimum rolling thickness of asymmetrical rolling only exists within a specific range of cross-shear ratio, which is termed the cross-shear zone proportion of the whole de- formation zone. Numerical computation was carried out to obtain a discrete solution of the minimum rolling thick- ness. Experiments were designed to investigate the influence factors on cross-shear ratio. Finally, experimental re- sults prove the correctness of the improved formula given.展开更多
The Tumen River had failed to meet Grade Ⅲ and Ⅳ levels in the environmental quality standard for surface water, and had exceeded Grade Ⅴ level. Surface water pollution is serious. The major excessive standard poll...The Tumen River had failed to meet Grade Ⅲ and Ⅳ levels in the environmental quality standard for surface water, and had exceeded Grade Ⅴ level. Surface water pollution is serious. The major excessive standard pollutants were COD Mn and SS. After taking effective treatment steps, the worsening trend of water pollution will be basically under control. But the change of runoff in the Tumen River is large in a year, especially during as long as five month freezing period, smaller flow and lower temperature of river waters led to weak dilution and self purification capacity. The water quality of the Tumen River will not reach the appoint functional water quality standards, even if sewage meets discharge standard, which will influence water resources utilization in the lower reaches of the Tumen River and regional economic development. Therefore water pollution has become the major restrictive factor of the development of the Tumen River area.展开更多
The article deals with an economic order quantity (EOQ) inventory model for deteriorating items in which the supplier provides the purchaser a permissible delay in payment. This is so when deterioration of units in th...The article deals with an economic order quantity (EOQ) inventory model for deteriorating items in which the supplier provides the purchaser a permissible delay in payment. This is so when deterioration of units in the inventory is subject to constant deterioration rate, demand rate is quadratic function of time and salvage value is associated with the deteriorated units. Shortages in the system are not allowed to occur. A mathematical formulation is developed when the supplier offers a permissible delay period to the customers under two circumstances: 1) when delay period is less than the cycle of time;and 2) when delay period is greater than the cycle of time. The method is suitable for the items like state-of-the-art aircrafts, super computers, laptops, android mobiles, seasonal items and machines and their spare parts. A solution procedure algorithm is given for finding the optimal order quantity which minimizes the total cost of an inventory system. The article includes numerical examples to support the effectiveness of the developed model. Finally, sensitivity analysis on some parameters on optimal solution is provided.展开更多
Hydrocarbon wastes generated from remediation activities contain Total Petroleum Hydrocarbon (TPH), Polyaromatic Hydrocarbon (PAH) and Heavy Metals whose respective concentrations are yet to be determined. There is li...Hydrocarbon wastes generated from remediation activities contain Total Petroleum Hydrocarbon (TPH), Polyaromatic Hydrocarbon (PAH) and Heavy Metals whose respective concentrations are yet to be determined. There is limited available literature particularly in Nigeria, on whether the concentration of these wastes after treatment exceeds permissible limits. The present work aims to determine the concentration of petroleum hydrocarbon in the residual ash from the treated (incinerated) oily wastes from the Bodo-Ogoni remediation activities. Oily wastes residual ash samples were collected from six treatment sites, each divided into four replicates in a Completely Randomized Design. A total of twenty-four residual ash samples were collected and taken to National Oil Spill Detection and Response Agency (NOSDRA) Reference Laboratory, Port Harcourt for extraction. The concentration of TPH, PAH and heavy metals in untreated hydrocarbon wastes were also determined and used for the control experiment. The extracts were analyzed using AGILENT 7890A-GC and Atomic Absorption Spectrophotometer (AAS) modelled 240FS, manufactured in USA. The results show six residual pollutants;Cadmium, Lead, Zinc, Manganese, TPH and PAH below the Nigeria Department of Petroleum Resources (DPR) Intervention Level but exceeded the DPR Target Level for TPH and PAH. The descending order of concentration of PAH obtained from the treatment sites gwere;1.24 + 2.4 mg/kg (Paschal), 4.76 + 7.48 mg/kg (ITS), 10.46 + 14.68 mg/kg (TMCH) and 16.14 + 6.36 mg/kg (Mosab). Similarly, the concentration of TPH was 320.18 + 355.13 mg/kg (TMCH), 463.25 + 205.29 mg/kg (ICREN) and 501.11 + 300.79 mg/kg (Networld) against TPH 12,000 mg/kg, PAH 23 mg/kg, Cadmium 0.15 mg/kg, Lead 0.59 mg/kg, Zinc 3.45 mg/kg and Manganese 2.8 mg/kg (untreated wastes). Two treatment sites only recorded concentration of heavy metals, while four reformed inefficiently and couldn’t detect the concentration of some residual pollutants in the ash samples and consequently, recorded below detecta展开更多
Abstract： This paper presented the results from the study of irrigation erosion of irrigated lands in southern Ka- zakhstan. The main purpose of the work is the conservation of the fertility of irrigated soils, and t...Abstract： This paper presented the results from the study of irrigation erosion of irrigated lands in southern Ka- zakhstan. The main purpose of the work is the conservation of the fertility of irrigated soils, and then the soils of the upper, middle and lower sections of the slopes at the experimental site were studied. Based on field investigations, authors studied the water resistance of aggregates of gray-brown soils and light gray soils before and after irrigation and qualitative indicators of changes in physical and chemical properties of structured soils in irrigation were de- termined by conventional methods of soil research. The results indicated that the changes in the physical properties of soils by using polymeric compounds created a fundamentally new opportunity to control water erosion of soils.展开更多
This research is focused on the search of a biomass for the sequestration of fluoride from drinking water. Defluoridation of water was studied by batch experiments in biosorption process. The biomass was found to redu...This research is focused on the search of a biomass for the sequestration of fluoride from drinking water. Defluoridation of water was studied by batch experiments in biosorption process. The biomass was found to reduce fluoride to permissible limit 1.5 mg/L as prescribed by WHO. The efficiency of the sorption process was investigated under different experimental parameters such as pH 7, standing time 120 min and biomass doses 7.0 g with 5 mg/L concentration of fluoride. Neutral pH was identified as the optimum condition of the medium and 120 minutes was the best contact time for maximum fluoride adsorption. The experimental data was found good fitting to Langmuir and Freundlich isotherm models. In interference study tolerable effect was found with 50 mg/L concentration of co-ions, whereas increasing the concentration of co-ions retarded the fluoride removal capacity in some extent. FT-IR spectrum analysis showed fluoride binding in the different frequency ranges of the biomass. Eventually, this plant biomass is recommended as a suitable and low cost adsorbent to reduce fluoride into standard permissible limit.展开更多
In this paper,economic order quantity(EOQ)inventory model is considered subject to promotional efforts.We adopt a demand function which is dependent on sales teams’initiatives in which shortages are allowed which are...In this paper,economic order quantity(EOQ)inventory model is considered subject to promotional efforts.We adopt a demand function which is dependent on sales teams’initiatives in which shortages are allowed which are completely backlogged under the condition of permissible delay in payments with timedependent holding cost.The main objective of this paper is to determine the optimal replenishment schedule and optimal order quantity to maximize the total profit.Expressions for various optimal indices are provided.First,we prove that a unique optimal replenishment schedule exists.Second,we present an effective iterative algorithm to obtain the optimal solution.Furthermore,we establish some useful theorems to characterize the optimal solution to determine the values of replenishment schedule and optimal order quantity.Third,we prove that the total profit is a concave function via differential calculus and present numerical examples using SCILAB 5.5.0 to illustrate the model.Finally,we extend the numerical example by performing a sensitivity analysis of the model parameters and discuss managerial insights.This study suggests to the management of firms to determine the optimal order quantity,optimal inventory cycle length and sales teams’initiatives/promotional effort in order to achieve their maximum profits.展开更多
The most visible uncontrolled landfill sites were selected in the western and eastern parts of the territory of Georgia. Particularly, in eastern Georgia the regions of Mtskheta-Mtianeti and Kvemo Kartli have been res...The most visible uncontrolled landfill sites were selected in the western and eastern parts of the territory of Georgia. Particularly, in eastern Georgia the regions of Mtskheta-Mtianeti and Kvemo Kartli have been researched;and in western Georgia Imereti and Samtskhe-Javakheti correspondingly. Both chemical and microbiological analyses were conducted in the samples taken from their adjacent territories. In case the landfill site is located near the river, during field works using portable equipment main physical-chemical indicators of surface waters were determined. After processing of the obtained results the corresponding estimations were provided. The risks due to the environmental pollution and negative impacts on population health were assessed.展开更多
We have formulated 3 permissible levels of respiratory resistance for aircraft oxygen equipment in China based on a comprehensive analysis of the results of human pkysiological experiments and feasibility of technolog...We have formulated 3 permissible levels of respiratory resistance for aircraft oxygen equipment in China based on a comprehensive analysis of the results of human pkysiological experiments and feasibility of technological design and performance with reference to existing standards and data. The ideal level can be used as a basic human physiological criterion. The applied permissible level is a criterion that must be followed in the process of design and production. The permissible level during maximum flow rate is presented as an extended allowable criterion for possible exceeding of the stable level for a short time.展开更多
This work presents the hydrologic estimations of the hydraulic underground arched culvert channel (UACC) in Sabinal Basin, Chiapas, México and the hydrological problems associated with it, such as the erosion phe...This work presents the hydrologic estimations of the hydraulic underground arched culvert channel (UACC) in Sabinal Basin, Chiapas, México and the hydrological problems associated with it, such as the erosion phenomenon and abrasion cavity formation in it. On the other hand, the maximum flows that the UACC could transport were analyzed, concluding that it no longer has the hydraulic capacity to transport the flow rate associated to return periods equal to or greater than five years and that maximum permissible velocity UACC’s bottom is 3 m/s.展开更多
Geothermal with features of large reserves and non-pollution has been one of the most important energy. China has significant geothermal resources. There are rich hydrothermal resources in Xinji, which has been in dev...Geothermal with features of large reserves and non-pollution has been one of the most important energy. China has significant geothermal resources. There are rich hydrothermal resources in Xinji, which has been in development for 5 years. However, hot water continues to decrease because of extensive exploitation and utilization. We selected exploration area as study area, build a set of numerical models of Guantao formation on the basis of actual geological conditions. We get the distribution of hydraulic conductivity from 1.7 m/d to 1.9 m/d by parameter inversion using historical water level monitoring data, and simulation effect is good. We calculate the maximum permissible exploitation under the limitation of 200 m in depth in 50 years which is about 2.2 million m3/a. The results will provide theoretic support for plan making of geothermal exploitation.展开更多
The purpose of this inventory model is to investigate the retailer’s optimal replenishment policy under permissible delay in payments. In this paper, we assume that the supplier would offer the retailer partially per...The purpose of this inventory model is to investigate the retailer’s optimal replenishment policy under permissible delay in payments. In this paper, we assume that the supplier would offer the retailer partially permissible delay in payments when the order quantity is smaller than a predetermined quantity (W). The most inventory systems are usually formed without considering the effect of deterioration of items which deteriorate continuously like fresh fruits, vegetables etc. Here we consider the loss due to deterioration. In real world situation, the demand of some items varies with change of seasons and occasions. So it is more significant if the loss of deterioration is time dependent. Considering all these facts, this inventory model has been developed to make more realistic and flexible marketing policy to the retailer, also establish the result by ANOVA analysis by treating different model parameters as factors.展开更多
Kenya like most of sub-Saharan Africa is reliant predominantly on agriculture and natural resources;which include land, water, minerals and fisheries, but the most dominant of which </span></span><span&...Kenya like most of sub-Saharan Africa is reliant predominantly on agriculture and natural resources;which include land, water, minerals and fisheries, but the most dominant of which </span></span><span><span><span>are</span></span></span><span><span><span> wildlife and forestry. Unlike minerals which are by law vested in the government and can only be extracted by it and not the citizenry, wildlife and forestry are resources that the citizens may utilize in their day to day lives to meet their needs. Apart from their consumptive uses, there are also non-consumptive uses and values of wild animals and forests;such as their intrinsic ecological value as gene banks, as well as their scenic value for viewing. These are essentially conventional values and uses. They are largely formal and universal ones that are universally obtaining across </span></span></span><span><span><span>the </span></span></span><span><span><span>world irrespective of the levels of civilization or cultural identity, and </span></span></span><span><span><span>are </span></span></span><span><span><span>even compatible with modernity. Apart from these, there are some wildlife and forestry uses </span></span></span><span><span><span>which</span></span></span><span><span><span> </span></span></span><span><span><span>are </span></span></span><span><span><span>unique to the typical African way of life as part of old traditional customs that have existed from earlier times. These are what are in this paper referred to as “traditional customary uses”. These uses are largely informal, rudimentary and archaic. They are nevertheless critical in the endemic African way of life and represent the inextricable rudimentary technologically bereft relationship between the African people and their natural resources. Under the country’s existing laws, some of these uses are prohibited and criminal sanctions prescribed to enforce their proscription, hence cannot be enjoyed or practiced. There are however others that the law</span></span></span><span><span><sp展开更多
Dynamic soaring is a flight maneuver to exploit gradient wind field to extend endurance and traveling distance.Optimal trajectories for permissible wind conditions are generated for loitering dynamic soaring as well a...Dynamic soaring is a flight maneuver to exploit gradient wind field to extend endurance and traveling distance.Optimal trajectories for permissible wind conditions are generated for loitering dynamic soaring as well as for traveling patterns with a small unmanned aerial vehicle.The efficient direct collection approach based on the Runge-Kutta integrator is used to solve the optimization problem.The fast convergence of the optimization process leads to the potential for real-time applications.Based on the results of trajectory optimizations,the general permissible wind conditions which involve the allowable power law exponents and feasible reference wind strengths supporting dynamic soaring are proposed.Increasing the smallest allowable wingtip clearance to trade for robustness and safety of the vehicle system and improving the maximum traveling speed results in shrunken permissible domain of wind conditions for loitering and traveling dynamic soaring respectively.Sensitivity analyses of vehicle model parameters show that properly reducing the wingspan and increasing the maximum lift-to-drag ratio and the wing loading can enlarge the permissible domain.Permissible domains for different traveling directions show that the downwind dynamic soaring benefitting from the drift is more efficient than the upwind traveling pattern in terms of permissible domain size and net traveling speed.展开更多
Laboratory tests revealed that the behavior of brick masonry under compressive cyclic loading is characterized by three distinct stress-strain curves. These three curves are termed as envelope curve, common point curv...Laboratory tests revealed that the behavior of brick masonry under compressive cyclic loading is characterized by three distinct stress-strain curves. These three curves are termed as envelope curve, common point curve and stability point curve. The envelope curve is obtained by superimposing the cyclic peaks on the monotonic stress-strain curve. The common point curve is the locus of intersection points of loading and unloading curves of the cycles. If for the same cycle, the loading and unloading are repeated several times, the intersection points of loading and unloading paths will stabilize at a lower bound. The locus of these stabilized points （lower bound points） of all cycles form the stability point curve. Therefore, the stability point curve can be used as a measure for the allowable stress for masonry under cyclic loadings. The proposed cyclic allowable stress level is associated with the accumulation of residual （plastic） strain levels as a result of cyclic loading history. The permissible stress level was found to be about two thirds of the cyclic peak stress of the specimen.展开更多
High concentrations of antimony(Sb) in soils and vegetables can cause potential health risk. However, the effect of Sb on the growth and response of crops are not well known and to date, there is still no Sb limit sta...High concentrations of antimony(Sb) in soils and vegetables can cause potential health risk. However, the effect of Sb on the growth and response of crops are not well known and to date, there is still no Sb limit standard for Allitic Udic Ferrisols in China. In this study, a greenhouse experiment was carried out to investigate the effect of antimony(Sb) on biomass, physiological performances,and macro- and micronutrient element concentrations of green Chinese cabbage(Brassica chinensis L.), as well as enzyme activities,in Allitic Udic Ferrisols from Hunan Province, China. Antimony was supplied at rates of 0(control), 2, 5, 10, 20, and 50 mg kg-1and thus with the background value of 1.0 mg kg-1, the Sb concentrations in the treated soil samples were 1, 3, 6, 11 21, and 51 mg kg-1, respectively. The results showed the leaf biomass and ascorbic acid content of cabbage significantly(P < 0.05) decreased by 30.6% and 48.3%, respectively, and soil urease and dehydrogenase activities also significantly(P < 0.05) decreased by 33.6%and 32.5%, respectively, when soil Sb concentration was 21 mg kg-1as compared with the control. The uptake of essential nutrient elements such as Mg, Cu, and Zn by cabbage was obviously affected, while the leaf soluble sugar content slightly changed when the soil Sb concentration exceeded 21 mg kg-1. Based on cabbage physiological responses and soil enzyme activities, the permissible concentration of 21 mg kg-1for Sb in Allitic Udic Ferrisols should be recommended.展开更多
文摘Mining activities in the Copperbelt province of Zambia have been of great environmental concern, despite recorded improvements in the socio-economic sector. Heavy metal contamination of soils resulting from depositing mine tailings and rock waste has posed possible health risks for communities nearer such facilities. The current study was conducted around residential homes surrounding Kitwe slimes (TD25). This work investigated levels of Co, Cu, Fe, Mn and Pb in the soils, and avocado and lemons fruits, growing near TD25. Heavy metals were analyzed using Atomic Absorption Spectrophotometer. The work further assessed the estimated daily intake (EDI) associated with potential health risks to humans. In the soil, concentration levels of heavy metals showed a trend in the order: Fe > Cu > Mn > Co > Pb. Heavy metal contents in avocado and lemon fruits at 200 and 400 m away from TD25, all had p-values < 0.05. The distances from the suspect source (TD25) to where the fruit trees were grown, had no influence on their concentration in the fruit samples. Fruit sample results showed that Fe had the highest EDI of 0.22 mg·kg<sup>-1</sup> (avocado) and 0.14 mg·kg<sup>-1</sup> (lemon), though both results were far below the FAO/WHO standard range (12.5 - 19.6 mg·kg<sup>-1</sup>). For both fruits, Co and Pb results were negligible. The concentration of the five heavy metals in avocado and lemon fruits grown around Kitwe slimes did not pose any health risks to the consumers.
基金Sponsored by National Natural Science Foundation of China(50974039)
文摘The minimum rolling thickness in asymmetrical rolling was analyzed compared with that in symmetrical rolling. The differential equilibrium equations on forces were established to calculate the asymmetrical rolling force equation by slab method. An implicit expression of the minimum rolling thickness was then derived from the rolling force equation and Hitehcock equation. The results show that permissible minimum rolling thickness of asymmetrical rolling only exists within a specific range of cross-shear ratio, which is termed the cross-shear zone proportion of the whole de- formation zone. Numerical computation was carried out to obtain a discrete solution of the minimum rolling thick- ness. Experiments were designed to investigate the influence factors on cross-shear ratio. Finally, experimental re- sults prove the correctness of the improved formula given.
文摘The Tumen River had failed to meet Grade Ⅲ and Ⅳ levels in the environmental quality standard for surface water, and had exceeded Grade Ⅴ level. Surface water pollution is serious. The major excessive standard pollutants were COD Mn and SS. After taking effective treatment steps, the worsening trend of water pollution will be basically under control. But the change of runoff in the Tumen River is large in a year, especially during as long as five month freezing period, smaller flow and lower temperature of river waters led to weak dilution and self purification capacity. The water quality of the Tumen River will not reach the appoint functional water quality standards, even if sewage meets discharge standard, which will influence water resources utilization in the lower reaches of the Tumen River and regional economic development. Therefore water pollution has become the major restrictive factor of the development of the Tumen River area.
文摘The article deals with an economic order quantity (EOQ) inventory model for deteriorating items in which the supplier provides the purchaser a permissible delay in payment. This is so when deterioration of units in the inventory is subject to constant deterioration rate, demand rate is quadratic function of time and salvage value is associated with the deteriorated units. Shortages in the system are not allowed to occur. A mathematical formulation is developed when the supplier offers a permissible delay period to the customers under two circumstances: 1) when delay period is less than the cycle of time;and 2) when delay period is greater than the cycle of time. The method is suitable for the items like state-of-the-art aircrafts, super computers, laptops, android mobiles, seasonal items and machines and their spare parts. A solution procedure algorithm is given for finding the optimal order quantity which minimizes the total cost of an inventory system. The article includes numerical examples to support the effectiveness of the developed model. Finally, sensitivity analysis on some parameters on optimal solution is provided.
文摘Hydrocarbon wastes generated from remediation activities contain Total Petroleum Hydrocarbon (TPH), Polyaromatic Hydrocarbon (PAH) and Heavy Metals whose respective concentrations are yet to be determined. There is limited available literature particularly in Nigeria, on whether the concentration of these wastes after treatment exceeds permissible limits. The present work aims to determine the concentration of petroleum hydrocarbon in the residual ash from the treated (incinerated) oily wastes from the Bodo-Ogoni remediation activities. Oily wastes residual ash samples were collected from six treatment sites, each divided into four replicates in a Completely Randomized Design. A total of twenty-four residual ash samples were collected and taken to National Oil Spill Detection and Response Agency (NOSDRA) Reference Laboratory, Port Harcourt for extraction. The concentration of TPH, PAH and heavy metals in untreated hydrocarbon wastes were also determined and used for the control experiment. The extracts were analyzed using AGILENT 7890A-GC and Atomic Absorption Spectrophotometer (AAS) modelled 240FS, manufactured in USA. The results show six residual pollutants;Cadmium, Lead, Zinc, Manganese, TPH and PAH below the Nigeria Department of Petroleum Resources (DPR) Intervention Level but exceeded the DPR Target Level for TPH and PAH. The descending order of concentration of PAH obtained from the treatment sites gwere;1.24 + 2.4 mg/kg (Paschal), 4.76 + 7.48 mg/kg (ITS), 10.46 + 14.68 mg/kg (TMCH) and 16.14 + 6.36 mg/kg (Mosab). Similarly, the concentration of TPH was 320.18 + 355.13 mg/kg (TMCH), 463.25 + 205.29 mg/kg (ICREN) and 501.11 + 300.79 mg/kg (Networld) against TPH 12,000 mg/kg, PAH 23 mg/kg, Cadmium 0.15 mg/kg, Lead 0.59 mg/kg, Zinc 3.45 mg/kg and Manganese 2.8 mg/kg (untreated wastes). Two treatment sites only recorded concentration of heavy metals, while four reformed inefficiently and couldn’t detect the concentration of some residual pollutants in the ash samples and consequently, recorded below detecta
基金supported by the International Science & Technology Cooperation Program of China(2010DFA92720)the Department of Ecology in Kazakh Research Institute of Soil Science and Agrochemistry named after Uspanov, Almaty, Kazakhstan
文摘Abstract： This paper presented the results from the study of irrigation erosion of irrigated lands in southern Ka- zakhstan. The main purpose of the work is the conservation of the fertility of irrigated soils, and then the soils of the upper, middle and lower sections of the slopes at the experimental site were studied. Based on field investigations, authors studied the water resistance of aggregates of gray-brown soils and light gray soils before and after irrigation and qualitative indicators of changes in physical and chemical properties of structured soils in irrigation were de- termined by conventional methods of soil research. The results indicated that the changes in the physical properties of soils by using polymeric compounds created a fundamentally new opportunity to control water erosion of soils.
文摘This research is focused on the search of a biomass for the sequestration of fluoride from drinking water. Defluoridation of water was studied by batch experiments in biosorption process. The biomass was found to reduce fluoride to permissible limit 1.5 mg/L as prescribed by WHO. The efficiency of the sorption process was investigated under different experimental parameters such as pH 7, standing time 120 min and biomass doses 7.0 g with 5 mg/L concentration of fluoride. Neutral pH was identified as the optimum condition of the medium and 120 minutes was the best contact time for maximum fluoride adsorption. The experimental data was found good fitting to Langmuir and Freundlich isotherm models. In interference study tolerable effect was found with 50 mg/L concentration of co-ions, whereas increasing the concentration of co-ions retarded the fluoride removal capacity in some extent. FT-IR spectrum analysis showed fluoride binding in the different frequency ranges of the biomass. Eventually, this plant biomass is recommended as a suitable and low cost adsorbent to reduce fluoride into standard permissible limit.
文摘In this paper,economic order quantity(EOQ)inventory model is considered subject to promotional efforts.We adopt a demand function which is dependent on sales teams’initiatives in which shortages are allowed which are completely backlogged under the condition of permissible delay in payments with timedependent holding cost.The main objective of this paper is to determine the optimal replenishment schedule and optimal order quantity to maximize the total profit.Expressions for various optimal indices are provided.First,we prove that a unique optimal replenishment schedule exists.Second,we present an effective iterative algorithm to obtain the optimal solution.Furthermore,we establish some useful theorems to characterize the optimal solution to determine the values of replenishment schedule and optimal order quantity.Third,we prove that the total profit is a concave function via differential calculus and present numerical examples using SCILAB 5.5.0 to illustrate the model.Finally,we extend the numerical example by performing a sensitivity analysis of the model parameters and discuss managerial insights.This study suggests to the management of firms to determine the optimal order quantity,optimal inventory cycle length and sales teams’initiatives/promotional effort in order to achieve their maximum profits.
文摘The most visible uncontrolled landfill sites were selected in the western and eastern parts of the territory of Georgia. Particularly, in eastern Georgia the regions of Mtskheta-Mtianeti and Kvemo Kartli have been researched;and in western Georgia Imereti and Samtskhe-Javakheti correspondingly. Both chemical and microbiological analyses were conducted in the samples taken from their adjacent territories. In case the landfill site is located near the river, during field works using portable equipment main physical-chemical indicators of surface waters were determined. After processing of the obtained results the corresponding estimations were provided. The risks due to the environmental pollution and negative impacts on population health were assessed.
文摘We have formulated 3 permissible levels of respiratory resistance for aircraft oxygen equipment in China based on a comprehensive analysis of the results of human pkysiological experiments and feasibility of technological design and performance with reference to existing standards and data. The ideal level can be used as a basic human physiological criterion. The applied permissible level is a criterion that must be followed in the process of design and production. The permissible level during maximum flow rate is presented as an extended allowable criterion for possible exceeding of the stable level for a short time.
文摘This work presents the hydrologic estimations of the hydraulic underground arched culvert channel (UACC) in Sabinal Basin, Chiapas, México and the hydrological problems associated with it, such as the erosion phenomenon and abrasion cavity formation in it. On the other hand, the maximum flows that the UACC could transport were analyzed, concluding that it no longer has the hydraulic capacity to transport the flow rate associated to return periods equal to or greater than five years and that maximum permissible velocity UACC’s bottom is 3 m/s.
基金supported by thermal response test(TRT)and numerical modeling with vertical ground heat exchanger in media sand(41302189)the research on the behavior characteristic of As and REE in high temperature geothermal fluid(1415042249)geothermal survey of Xiamen-Qiongbei region in Southeast coastal(12120115045901)
文摘Geothermal with features of large reserves and non-pollution has been one of the most important energy. China has significant geothermal resources. There are rich hydrothermal resources in Xinji, which has been in development for 5 years. However, hot water continues to decrease because of extensive exploitation and utilization. We selected exploration area as study area, build a set of numerical models of Guantao formation on the basis of actual geological conditions. We get the distribution of hydraulic conductivity from 1.7 m/d to 1.9 m/d by parameter inversion using historical water level monitoring data, and simulation effect is good. We calculate the maximum permissible exploitation under the limitation of 200 m in depth in 50 years which is about 2.2 million m3/a. The results will provide theoretic support for plan making of geothermal exploitation.
文摘The purpose of this inventory model is to investigate the retailer’s optimal replenishment policy under permissible delay in payments. In this paper, we assume that the supplier would offer the retailer partially permissible delay in payments when the order quantity is smaller than a predetermined quantity (W). The most inventory systems are usually formed without considering the effect of deterioration of items which deteriorate continuously like fresh fruits, vegetables etc. Here we consider the loss due to deterioration. In real world situation, the demand of some items varies with change of seasons and occasions. So it is more significant if the loss of deterioration is time dependent. Considering all these facts, this inventory model has been developed to make more realistic and flexible marketing policy to the retailer, also establish the result by ANOVA analysis by treating different model parameters as factors.
文摘Kenya like most of sub-Saharan Africa is reliant predominantly on agriculture and natural resources;which include land, water, minerals and fisheries, but the most dominant of which </span></span><span><span><span>are</span></span></span><span><span><span> wildlife and forestry. Unlike minerals which are by law vested in the government and can only be extracted by it and not the citizenry, wildlife and forestry are resources that the citizens may utilize in their day to day lives to meet their needs. Apart from their consumptive uses, there are also non-consumptive uses and values of wild animals and forests;such as their intrinsic ecological value as gene banks, as well as their scenic value for viewing. These are essentially conventional values and uses. They are largely formal and universal ones that are universally obtaining across </span></span></span><span><span><span>the </span></span></span><span><span><span>world irrespective of the levels of civilization or cultural identity, and </span></span></span><span><span><span>are </span></span></span><span><span><span>even compatible with modernity. Apart from these, there are some wildlife and forestry uses </span></span></span><span><span><span>which</span></span></span><span><span><span> </span></span></span><span><span><span>are </span></span></span><span><span><span>unique to the typical African way of life as part of old traditional customs that have existed from earlier times. These are what are in this paper referred to as “traditional customary uses”. These uses are largely informal, rudimentary and archaic. They are nevertheless critical in the endemic African way of life and represent the inextricable rudimentary technologically bereft relationship between the African people and their natural resources. Under the country’s existing laws, some of these uses are prohibited and criminal sanctions prescribed to enforce their proscription, hence cannot be enjoyed or practiced. There are however others that the law</span></span></span><span><span><sp
文摘Dynamic soaring is a flight maneuver to exploit gradient wind field to extend endurance and traveling distance.Optimal trajectories for permissible wind conditions are generated for loitering dynamic soaring as well as for traveling patterns with a small unmanned aerial vehicle.The efficient direct collection approach based on the Runge-Kutta integrator is used to solve the optimization problem.The fast convergence of the optimization process leads to the potential for real-time applications.Based on the results of trajectory optimizations,the general permissible wind conditions which involve the allowable power law exponents and feasible reference wind strengths supporting dynamic soaring are proposed.Increasing the smallest allowable wingtip clearance to trade for robustness and safety of the vehicle system and improving the maximum traveling speed results in shrunken permissible domain of wind conditions for loitering and traveling dynamic soaring respectively.Sensitivity analyses of vehicle model parameters show that properly reducing the wingspan and increasing the maximum lift-to-drag ratio and the wing loading can enlarge the permissible domain.Permissible domains for different traveling directions show that the downwind dynamic soaring benefitting from the drift is more efficient than the upwind traveling pattern in terms of permissible domain size and net traveling speed.
文摘Laboratory tests revealed that the behavior of brick masonry under compressive cyclic loading is characterized by three distinct stress-strain curves. These three curves are termed as envelope curve, common point curve and stability point curve. The envelope curve is obtained by superimposing the cyclic peaks on the monotonic stress-strain curve. The common point curve is the locus of intersection points of loading and unloading curves of the cycles. If for the same cycle, the loading and unloading are repeated several times, the intersection points of loading and unloading paths will stabilize at a lower bound. The locus of these stabilized points （lower bound points） of all cycles form the stability point curve. Therefore, the stability point curve can be used as a measure for the allowable stress for masonry under cyclic loadings. The proposed cyclic allowable stress level is associated with the accumulation of residual （plastic） strain levels as a result of cyclic loading history. The permissible stress level was found to be about two thirds of the cyclic peak stress of the specimen.
基金supported by the National Natural Science Foundation of China(No.41201492)the Science and Technology Project of Changsha City,China(No.K1003056-31)
文摘High concentrations of antimony(Sb) in soils and vegetables can cause potential health risk. However, the effect of Sb on the growth and response of crops are not well known and to date, there is still no Sb limit standard for Allitic Udic Ferrisols in China. In this study, a greenhouse experiment was carried out to investigate the effect of antimony(Sb) on biomass, physiological performances,and macro- and micronutrient element concentrations of green Chinese cabbage(Brassica chinensis L.), as well as enzyme activities,in Allitic Udic Ferrisols from Hunan Province, China. Antimony was supplied at rates of 0(control), 2, 5, 10, 20, and 50 mg kg-1and thus with the background value of 1.0 mg kg-1, the Sb concentrations in the treated soil samples were 1, 3, 6, 11 21, and 51 mg kg-1, respectively. The results showed the leaf biomass and ascorbic acid content of cabbage significantly(P < 0.05) decreased by 30.6% and 48.3%, respectively, and soil urease and dehydrogenase activities also significantly(P < 0.05) decreased by 33.6%and 32.5%, respectively, when soil Sb concentration was 21 mg kg-1as compared with the control. The uptake of essential nutrient elements such as Mg, Cu, and Zn by cabbage was obviously affected, while the leaf soluble sugar content slightly changed when the soil Sb concentration exceeded 21 mg kg-1. Based on cabbage physiological responses and soil enzyme activities, the permissible concentration of 21 mg kg-1for Sb in Allitic Udic Ferrisols should be recommended.
