More and more attention is being focused on saline water utilization in irrigation due to the shortage of fresh water to agriculture in many regions. For purpose of reducing the risks of using of saline water for irri...More and more attention is being focused on saline water utilization in irrigation due to the shortage of fresh water to agriculture in many regions. For purpose of reducing the risks of using of saline water for irrigation, the mechanism of soil moisture and salinity distribution and transport should be well understood for developing optimum management strategies. In this paper, field experiments were carried out at Junggar Basin, China, to study the effects of drip irrigation water quality and drip tape arrangement on distribution of soil salinity and soil moisture. Six treatments were designed, including two drip tape arrangement modes and three irrigation water concentration levels （0.24, 4.68, and 7.42 dS m^-l）. Results showed that, soil moisture content （SMC） directly beneath the drip tape in all treatments kept a relatively high value about 18% before boll opening stage; the SMC in the narrow strip in single tape arrangement （Ms） plot was obviously lower than that in the double tapes arrangement （Md） plot, indicating that less sufficient water was supplied under the same condition of irrigation depth, but there was no significant reduction in yield. Mulching had not significant influence on salt accumulation but the drip tape arrangement, under the same condition of irrigation water depth and quality, compared with Md, Ms reduced salt accumulation in root zone and brought about relatively high cotton yield.展开更多
This paper deals with the experimental investigation on Nusselt number,friction factor and thermal en-hancement factor of a double pipe heat exchanger equipped with twisted tape consisting wire nails(WN-TT) and plain ...This paper deals with the experimental investigation on Nusselt number,friction factor and thermal en-hancement factor of a double pipe heat exchanger equipped with twisted tape consisting wire nails(WN-TT) and plain twisted tapes(P-TT) with three different twist ratios of y 2.0,4.4 and 6.0. Test runs are conducted using the water as the working fluid with Reynolds number range between 2000 and 12000 for WN-TT and P-TT. It is found that Nusselt number,friction factor and thermal enhancement factor in the tube equipped with WN-TT appreciably higher than those in the tube fitted with P-TT and plain tube. Over the range considered Nusselt number,friction factor and thermal enhancement factor in a tube with WN-TT are respectively,1.08 to 1.31,1.1 to 1.75 and 1.05 to 1.13 times of those in tube with P-TT. The better performance of WN-TT is due to combined effects of the follow-ing factors:(1) common swirling flow generated by P-TT,(2) additional turbulence offered by the wire nails. Em-pirical correlations for Nusselt number,friction factor and thermal enhancement factor are also formulated from the experimental results of WN-TT and P-TT.展开更多
Dry adhesives inspired from climbing animals, such as geckos and spiders, rely on van der Waals forces to attach to the opposing surface. Biological fibrillar dry adhesives have a hierarchical structure closely resemb...Dry adhesives inspired from climbing animals, such as geckos and spiders, rely on van der Waals forces to attach to the opposing surface. Biological fibrillar dry adhesives have a hierarchical structure closely resembling a tree： the surface of the skin on the animal＇s feet is covered in arrays of slender micro-fibrils, each of which supports arrays of fibrils in submicron dimensions. These nano-meter size fibrils can conform closely to the opposing surfaces to induce van der Waals interaction. Bioinspired dry adhesives have been developed in research laboratories for more than a decade. To mimic the biological fibrillar adhesives, fibrillar structures have been prepared using a variety of materials and geometrical arrangements. In this review article, the mechanism and selected fabrication methods of fibrillar adhesives are summarized for future reference in adhesive development. Robotic applications of these bioinspired adhesives are also introduced in this article. Various successful appli- cations of bioinspired fibrillar adhesives can shed light on developing smart adhesives for use in automation.展开更多
Heat transfer,friction factor and thermal enhancement factor characteristics of a double pipe heat exchanger fitted with square-cut twisted tapes（STT） and plain twisted tapes（PTT） are investigated experimentally u...Heat transfer,friction factor and thermal enhancement factor characteristics of a double pipe heat exchanger fitted with square-cut twisted tapes（STT） and plain twisted tapes（PTT） are investigated experimentally using the water as working fluid.The tapes（STT and PTT） have three twist ratios（y=2.0,4.4 and 6.0） and the Reynolds number ranges from 2000 to 12000.The experimental results reveal that heat transfer rate,friction factor and thermal enhancement factor in the tube equipped with STT are significantly higher than those fitted with PTT. The additional disturbance and secondary flow in the vicinity of the tube wall generated by STT are higher compared to that induced by the PTT is referred as the reason for better performance.Over the range considered,the Nusselt number,friction factor and thermal enhancement factor in a tube with STT are respectively,1.03 to 1.14,1.05 to 1.25 and 1.02 to 1.06 times of those in tube with PTT.An empirical correlation is also formulated to match with experimental data of Nusselt number and friction factor for STT and PTT.展开更多
Background Inside out transobturator vaginal tape （TVT-O） and tension-free vaginal tape （TVT） are predominant surgical treatments for female stress urinary incontinence. This meta-analysis evaluated the complicati...Background Inside out transobturator vaginal tape （TVT-O） and tension-free vaginal tape （TVT） are predominant surgical treatments for female stress urinary incontinence. This meta-analysis evaluated the complications and cure rates of TVT-O versus TVT. Methods A comprehensive literature search was conducted according to the Cochrane Collaboration methodology to identify randomized controlled clinical trials with no language restriction. Two authors independently assessed papers for eligibility and methodological quality. Estimates were measured by relative risk with 95% confidence intervals. Outcome measures were objective cure, subjective cure and complications. Quality rating for each outcome of the meta-analysis and recommendations were performed by the Grading of Recommendations Assessment, Development, and Evaluation （GRADE） system. Results Twenty randomized controlled trials met the inclusion criteria, and a pooled estimate of effectiveness and complications was made. Relative risks with 95% confidence intervals for pooled effects under the fixed effects model were： 0.20 （0.09-0.45）, for bladder injury, 0.37 （0.16-0.86） for hematoma, and 2.35 （1.57-3.51） for postoperative pain, suggesting an 80% risk reduction of bladder injury, 63% risk reduction of hematoma, and a 1.35% risk elevation for postoperative pain with TVT-O. There was no significant difference between complications of urinary tract infection 1.14 （0.78-1.65）, lower urinary tract symptoms 1.60 （0.67-3.79）, recatheterization 0.93 （0.59-1.44）, and tape erosion 0.90 （0.48-1.67）, total objective cure rate 1.06 （0.39-2.84） and for the subjective cure rate 0.98 （0.93-1.04）. The quality rating for each outcome and recommendations was high for objective cure, bladder injury, hematoma, lower urinary tract symptoms, and tape erosion and moderate for subjective cure, pain, and urinary tract infection. Conclusions TVT-O is associated with a reduced risk of bladder injury and hematoma and an elevated risk of 展开更多
Automated tape placement is an important automated process used for fabrication of large composite structures in aeronautical industry. The carbon fiber composite parts realized with this process tend to replace the a...Automated tape placement is an important automated process used for fabrication of large composite structures in aeronautical industry. The carbon fiber composite parts realized with this process tend to replace the aluminum parts produced by high-speed machining. It is difficult to determine the appropriate width of the composite tape in automated tape placement. Wrinkling will appear in the tape if it does not suit for the mould surface. Thus, this paper deals with establishing placement suitability criteria of the composite tape for the mould surface. With the assumptions for ideal mapping and by applying some principles and theorems of differential geometry, the centerline trajectory of the composite tape is identified to follow the geodesic. The placement suitability of the composite tape is examined on three different types of non-developable mould surfaces and four criteria are derived. The developed criteria have been used to test the deposition process over several mould surfaces and the appropriate width for each mould surface is obtained by referring to these criteria.展开更多
The paper presents an experimental investigation on enhanced heat transfer and pressure loss characteristics by using single, double, triple, and quadruple twisted-tape inserts in a round tube having a uniform heat-fl...The paper presents an experimental investigation on enhanced heat transfer and pressure loss characteristics by using single, double, triple, and quadruple twisted-tape inserts in a round tube having a uniform heat-fluxed wall. The investigation has been conducted in the heat exchanger tube inserted with various twisted-tape numbers for co- and counter-twist arrangements for the turbulent air flow, Reynolds number （Re） from 5300 to 24000. The typical single twisted-tape inserts at two twist ratios, y/w = 4 and 5, are used as the base case, while the other multiple twisted-tape inserts are aty/w = 4 only. The experimental results of heat transfer and pressure drop in terms of Nusselt number （Nu） and friction factor 00, respectively, reveal that Nu increases with the increment of Re and of twisted-tape number. The values of Nu for the inserted tube are in a range of 1.15-2.12 times that for the plain tube while f is 1.9-4.1 times. The thermal enhancement factor of the inserted tube under similar pumping power is evaluated and found to be above unity except for the single and the double co-twisted tapes. The quadruple counter-twisted tape insert provides the maximum thermal performance.展开更多
In this review,the evolution of textured lead-free piezoceramics has been explored,primarily focusing on the technique of templated grain growth(TGG)and reactive-templated grain growth(RTGG),as an alternative to singl...In this review,the evolution of textured lead-free piezoceramics has been explored,primarily focusing on the technique of templated grain growth(TGG)and reactive-templated grain growth(RTGG),as an alternative to single crystals.The mechanics and properties of using template in guiding and orienting the ceramic grains into the same crystal orientation allow for piezoelectric properties approaching those of their single-crystal counterparts.The fabrication process was surveyed in depth,with focus placed on the tape casting process and numerous variables associated with aligning the template seeds in the ceramic matrix.The piezoelectric and ferroelectric properties of the textured ceramics are supposed to be a function of all parameters(tape casting,slurry formation,sintering profile,template properties)in an effort to determine the significance of their contributions to the properties.展开更多
基金supported by the National Natural Science Foundation of China(40771097)the Special Fund of Industrial(Agriculture)Research for Public Welfare of China(200903001)
文摘More and more attention is being focused on saline water utilization in irrigation due to the shortage of fresh water to agriculture in many regions. For purpose of reducing the risks of using of saline water for irrigation, the mechanism of soil moisture and salinity distribution and transport should be well understood for developing optimum management strategies. In this paper, field experiments were carried out at Junggar Basin, China, to study the effects of drip irrigation water quality and drip tape arrangement on distribution of soil salinity and soil moisture. Six treatments were designed, including two drip tape arrangement modes and three irrigation water concentration levels （0.24, 4.68, and 7.42 dS m^-l）. Results showed that, soil moisture content （SMC） directly beneath the drip tape in all treatments kept a relatively high value about 18% before boll opening stage; the SMC in the narrow strip in single tape arrangement （Ms） plot was obviously lower than that in the double tapes arrangement （Md） plot, indicating that less sufficient water was supplied under the same condition of irrigation depth, but there was no significant reduction in yield. Mulching had not significant influence on salt accumulation but the drip tape arrangement, under the same condition of irrigation water depth and quality, compared with Md, Ms reduced salt accumulation in root zone and brought about relatively high cotton yield.
文摘This paper deals with the experimental investigation on Nusselt number,friction factor and thermal en-hancement factor of a double pipe heat exchanger equipped with twisted tape consisting wire nails(WN-TT) and plain twisted tapes(P-TT) with three different twist ratios of y 2.0,4.4 and 6.0. Test runs are conducted using the water as the working fluid with Reynolds number range between 2000 and 12000 for WN-TT and P-TT. It is found that Nusselt number,friction factor and thermal enhancement factor in the tube equipped with WN-TT appreciably higher than those in the tube fitted with P-TT and plain tube. Over the range considered Nusselt number,friction factor and thermal enhancement factor in a tube with WN-TT are respectively,1.08 to 1.31,1.1 to 1.75 and 1.05 to 1.13 times of those in tube with P-TT. The better performance of WN-TT is due to combined effects of the follow-ing factors:(1) common swirling flow generated by P-TT,(2) additional turbulence offered by the wire nails. Em-pirical correlations for Nusselt number,friction factor and thermal enhancement factor are also formulated from the experimental results of WN-TT and P-TT.
文摘Dry adhesives inspired from climbing animals, such as geckos and spiders, rely on van der Waals forces to attach to the opposing surface. Biological fibrillar dry adhesives have a hierarchical structure closely resembling a tree： the surface of the skin on the animal＇s feet is covered in arrays of slender micro-fibrils, each of which supports arrays of fibrils in submicron dimensions. These nano-meter size fibrils can conform closely to the opposing surfaces to induce van der Waals interaction. Bioinspired dry adhesives have been developed in research laboratories for more than a decade. To mimic the biological fibrillar adhesives, fibrillar structures have been prepared using a variety of materials and geometrical arrangements. In this review article, the mechanism and selected fabrication methods of fibrillar adhesives are summarized for future reference in adhesive development. Robotic applications of these bioinspired adhesives are also introduced in this article. Various successful appli- cations of bioinspired fibrillar adhesives can shed light on developing smart adhesives for use in automation.
文摘Heat transfer,friction factor and thermal enhancement factor characteristics of a double pipe heat exchanger fitted with square-cut twisted tapes（STT） and plain twisted tapes（PTT） are investigated experimentally using the water as working fluid.The tapes（STT and PTT） have three twist ratios（y=2.0,4.4 and 6.0） and the Reynolds number ranges from 2000 to 12000.The experimental results reveal that heat transfer rate,friction factor and thermal enhancement factor in the tube equipped with STT are significantly higher than those fitted with PTT. The additional disturbance and secondary flow in the vicinity of the tube wall generated by STT are higher compared to that induced by the PTT is referred as the reason for better performance.Over the range considered,the Nusselt number,friction factor and thermal enhancement factor in a tube with STT are respectively,1.03 to 1.14,1.05 to 1.25 and 1.02 to 1.06 times of those in tube with PTT.An empirical correlation is also formulated to match with experimental data of Nusselt number and friction factor for STT and PTT.
文摘Background Inside out transobturator vaginal tape （TVT-O） and tension-free vaginal tape （TVT） are predominant surgical treatments for female stress urinary incontinence. This meta-analysis evaluated the complications and cure rates of TVT-O versus TVT. Methods A comprehensive literature search was conducted according to the Cochrane Collaboration methodology to identify randomized controlled clinical trials with no language restriction. Two authors independently assessed papers for eligibility and methodological quality. Estimates were measured by relative risk with 95% confidence intervals. Outcome measures were objective cure, subjective cure and complications. Quality rating for each outcome of the meta-analysis and recommendations were performed by the Grading of Recommendations Assessment, Development, and Evaluation （GRADE） system. Results Twenty randomized controlled trials met the inclusion criteria, and a pooled estimate of effectiveness and complications was made. Relative risks with 95% confidence intervals for pooled effects under the fixed effects model were： 0.20 （0.09-0.45）, for bladder injury, 0.37 （0.16-0.86） for hematoma, and 2.35 （1.57-3.51） for postoperative pain, suggesting an 80% risk reduction of bladder injury, 63% risk reduction of hematoma, and a 1.35% risk elevation for postoperative pain with TVT-O. There was no significant difference between complications of urinary tract infection 1.14 （0.78-1.65）, lower urinary tract symptoms 1.60 （0.67-3.79）, recatheterization 0.93 （0.59-1.44）, and tape erosion 0.90 （0.48-1.67）, total objective cure rate 1.06 （0.39-2.84） and for the subjective cure rate 0.98 （0.93-1.04）. The quality rating for each outcome and recommendations was high for objective cure, bladder injury, hematoma, lower urinary tract symptoms, and tape erosion and moderate for subjective cure, pain, and urinary tract infection. Conclusions TVT-O is associated with a reduced risk of bladder injury and hematoma and an elevated risk of
基金supported by the National Basic Research Program of China (No. 2013CB035805)the National Science and Technology Major Project of China (2010ZX04016-013)
文摘Automated tape placement is an important automated process used for fabrication of large composite structures in aeronautical industry. The carbon fiber composite parts realized with this process tend to replace the aluminum parts produced by high-speed machining. It is difficult to determine the appropriate width of the composite tape in automated tape placement. Wrinkling will appear in the tape if it does not suit for the mould surface. Thus, this paper deals with establishing placement suitability criteria of the composite tape for the mould surface. With the assumptions for ideal mapping and by applying some principles and theorems of differential geometry, the centerline trajectory of the composite tape is identified to follow the geodesic. The placement suitability of the composite tape is examined on three different types of non-developable mould surfaces and four criteria are derived. The developed criteria have been used to test the deposition process over several mould surfaces and the appropriate width for each mould surface is obtained by referring to these criteria.
基金the Thailand Research Fund(TRF)(Grant No.Ph D/0143/2552)
文摘The paper presents an experimental investigation on enhanced heat transfer and pressure loss characteristics by using single, double, triple, and quadruple twisted-tape inserts in a round tube having a uniform heat-fluxed wall. The investigation has been conducted in the heat exchanger tube inserted with various twisted-tape numbers for co- and counter-twist arrangements for the turbulent air flow, Reynolds number （Re） from 5300 to 24000. The typical single twisted-tape inserts at two twist ratios, y/w = 4 and 5, are used as the base case, while the other multiple twisted-tape inserts are aty/w = 4 only. The experimental results of heat transfer and pressure drop in terms of Nusselt number （Nu） and friction factor 00, respectively, reveal that Nu increases with the increment of Re and of twisted-tape number. The values of Nu for the inserted tube are in a range of 1.15-2.12 times that for the plain tube while f is 1.9-4.1 times. The thermal enhancement factor of the inserted tube under similar pumping power is evaluated and found to be above unity except for the single and the double co-twisted tapes. The quadruple counter-twisted tape insert provides the maximum thermal performance.
基金DMTC Limited(Australia).The authors have prepared this paper in accordance with the intellectual property rights granted to partners from the original DMTC project.
文摘In this review,the evolution of textured lead-free piezoceramics has been explored,primarily focusing on the technique of templated grain growth(TGG)and reactive-templated grain growth(RTGG),as an alternative to single crystals.The mechanics and properties of using template in guiding and orienting the ceramic grains into the same crystal orientation allow for piezoelectric properties approaching those of their single-crystal counterparts.The fabrication process was surveyed in depth,with focus placed on the tape casting process and numerous variables associated with aligning the template seeds in the ceramic matrix.The piezoelectric and ferroelectric properties of the textured ceramics are supposed to be a function of all parameters(tape casting,slurry formation,sintering profile,template properties)in an effort to determine the significance of their contributions to the properties.
