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激光烧蚀短程热效应 1

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Development of an analytical model to estimate the churning losses in high-speed axial piston pumps

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-021-0671-1

摘要： The axial piston pumps in aerospace applications are often characterized by high-speed rotation to achieve great power density. However, their internal rotating parts are fully immersed in the casing oil during operation, leading to considerable churning losses (more than 10% of total power losses) at high rotational speeds. The churning losses deserve much attention at the design stage of high-speed axial piston pumps, but accurate analytical models are not available to estimate the drag torque associated with the churning losses. In this paper, we derive the analytical expressions of the drag torque acting on the key rotating parts immersed in oil, including the cylinder block and the multiple pistons in a circular array. The calculated drag torque agrees well with the experimental data over a wide range of rotational speeds from 1500 to 12000 r/min. The presented analytical model provides practical guidelines for reducing the churning losses in high-speed axial piston pumps or motors.

关键词： axial piston pump     rotating parts     high rotational speed     churning losses     drag torque    

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NUTRIENT USE EFFICIENCY AND LOSSES OF INDUSTRIAL FARMS AND MIXED SMALLHOLDINGS: LESSONS FROM THE NORTH

《农业科学与工程前沿（英文）》 2021年 第8卷 第1期

摘要：

• Degree of integration of crop and livestock was insufficient on mixed smallholdings.

• Liquid manure discharges on industrial farms hamper the closing of nutrient loops.

• Coupling with local crop farms is encouraged to achieve integration of crop-livestock systems.

 

The proportion of industrial livestock in China has increased over the past 30 years, which increases animal performance but causes the decoupling of crop and livestock production. Here, we aimed to quantify nutrient flows, nutrient use efficiency, and nutrient losses in different livestock systems in the North China Plain based on the NUFER-farm model. Activity data were collected by face-to-face surveys on pig and dairy (41 livestock farms) during 2016–2018. The two systems included industrial farms and mixed smallholdings. In mixed smallholdings, 4.0% and 9.6% of pig and dairy feed dry matter (DM) were derived from household farmland, but 4.8% and 9.3% of manure DM recycled to household farmland. Nutrient use efficiency in industrial farms was higher than in mixed smallholdings at animal level, herd level, and system level. To produce 1 kg N and P in animal products, nutrient losses in industrial pig farms (2.0 kg N and 1.3 kg P) were lower than in mixed pig smallholdings, nutrient losses in industrial dairy farms (2.7 kg N and 2.2 kg P) were slightly higher than in mixed dairy smallholdings. Liquid manure discharge in industrial farms was the main losses pathway in contrast to mixed smallholdings. This study suggests that feed localization can reduce nutrient surpluses at the district level. It is necessary to improve manure management and increase the degree of integrated crop-livestock in smallholdings. In industrial farms, it is desirable to increase the liquid manure recycling ratio through cooperating livestock and crop production at the district level.

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HOTSPOTS OF NUTRIENT LOSSES TO AIR AND WATER: AN INTEGRATED MODELING APPROACH FOR EUROPEAN RIVER BASINS

《农业科学与工程前沿（英文）》 2023年 第10卷 第4期   页码 579-592 doi: 10.15302/J-FASE-2023526

摘要：

Nutrient pollution of air and water is a persistent problem in Europe. However, the pollution sources are often analyzed separately, preventing the formulation of integrative solutions. This study aimed to quantify the contribution of agriculture to air, river and coastal water pollution by nutrients. A new MARINA-Nutrients model was developed for Europe to calculate inputs of nitrogen (N) and phosphorus (P) to land and rivers, N emissions to air, and nutrient export to seas by river basins. Under current practice, inputs of N and P to land were 34.4 and 1.8 Tg·yr–1, respectively. However, only 12% of N and 3% of P reached the rivers. Agriculture was responsible for 55% of N and sewage for 67% of P in rivers. Reactive N emissions to air from agriculture were calculated at 4.0 Tg·yr–1. Almost two-fifths of N emissions to air were from animal housing and storage. Nearly a third of the basin area was considered as pollution hotspots and generated over half of N emissions to air and nutrient pollution in rivers. Over 25% of river export of N ended up in the Atlantic Ocean and of P in the Mediterranean Sea. These results could support environmental policies to reduce both air and water pollution simultaneously, and avoid pollution swapping.

关键词： agriculture     air-water modeling     European rivers     nutrient pollution     sewage systems     source attribution    

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GASEOUS REACTIVE NITROGEN LOSSES FROM ORCHARDS, VEGETABLES AND TEA PLANTATIONS

《农业科学与工程前沿（英文）》 2023年 第10卷 第2期   页码 155-166 doi: 10.15302/J-FASE-2022477

摘要：

● Gaseous N emissions from orchards, vegetables and tea plantations (OVT) are reviewed.

关键词： fruit     greenhouse gas     green development     fertilizer management     climate change    

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Exergy losses in premixed flames of dimethyl ether and hydrogen blends

Tongbin ZHAO, Jiabo ZHANG, Dehao JU, Zhen HUANG, Dong HAN

《能源前沿（英文）》 2019年 第13卷 第4期   页码 658-666 doi: 10.1007/s11708-019-0645-8

摘要： A second-law thermodynamic analysis was conducted for stoichiometric premixed dimethyl ether (DME)/hydrogen (H )/air flames at atmospheric pressure. The exergy losses from the irreversibility sources, i.e., chemical reaction, heat conduction and species diffusion, and those from partial combustion products were analyzed in the flames with changed fuel blends. It is observed that, regardless of the fuel blends, chemical reaction contributes most to the exergy losses, followed by incomplete combustion, and heat conduction, while mass diffusion has the least contribution to exergy loss. The results also indicate that increased H substitution decreases the exergy losses from reactions, conduction, and diffusion, primarily because of the flame thickness reduction at elevated H substitution. The decreases in exergy losses by chemical reactions and heat conduction are higher, but the exergy loss reduction by diffusion is slight. However, the exergy losses from incomplete combustion increase with H substitution, because the fractions of the unburned fuels and combustion intermediates, e.g., H and OH radical, increase. The overall exergy losses in the DME/H flames decrease by about 5% with increased H substitution from 0% to 100%.

关键词： second law analysis     flame     dimethyl ether (DME)     hydrogen     binary fuels    

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Test investigation on hydraulic losses in the discharge passage of an axial-flow pump

QIU Baoyun, CAO Haihong, JIANG Wei, GAO Zhaohui, WANG Fei

《机械工程前沿（英文）》 2007年 第2卷 第1期   页码 50-56 doi: 10.1007/s11465-007-0008-8

摘要： In a discharge passage with a guide blade discharge circulation and secondary flow because of bend pipe, the flow in a 1-channel discharge passage of an axial flow pump is a complicated spiral flow. For a 2-channel passage, the discharge in the left channel is bigger than that in the right, and the passage hydraulic losses are abnormal. In this study, the section current energy of the passage is accurately measured and determined with a 5-hole probe. The hydraulic loss characteristics are determined and analyzed. The methods deducing the hydraulic losses are investigated. The results indicate that the passage hydraulic losses are not proportional to the flow discharge. Compared with a circular pipe, the hydraulic losses of a divergent discharge passage are smaller and the pump assembly efficiency is 10% 30% higher. As for the 1-channel passage, the axial-flow pump outlet circulation is usually too big; the passage hydraulic losses are also big, but a small circulation can slightly reduce hydraulic losses. As for the 2-channel passage, discharges in the two channels are not equal and the hydraulic losses increase. The outlet guide blade with a small discharge circulation or without circulation could reduce discharge passage hydraulic losses and increase pump assembly efficiency by 6% 11%.
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Development and testing of a weather-based model to determine potential yield losses caused by potato

Alexey FILIPPOV, Maria KUZNETSOVA, Alexander ROGOZHIN, Olga IAKUSHEVA, Valentina DEMIDOVA, Natalia STATSYUK

《农业科学与工程前沿（英文）》 2018年 第5卷 第4期   页码 462-468 doi: 10.15302/J-FASE-2018239

摘要：

Late blight is one of the most important potato diseases. To minimize yield losses, various protective measures are used including fungicide application. Active use of fungicides results in a contamination of the environment. Therefore, crop protection strategies optimizing the number of treatments are of great interest. Using information about late blight development in an experimental potato field recorded over 30 seasons, a simulator to forecast yield losses caused by the disease was developed based on the number of 5-d periods favorable for reinfection of plants during a vegetation season. The simulator was successfully verified using independent data on the disease development from nine unprotected potato fields in the Netherlands and Germany. The average difference between the calculated and real yield losses did not exceed 5%. Using the simulator and weather data for a period of 2007-2017, yield losses were calculated for several areas of the Bryansk, Tambov, and Orenburg Regions of Russia. The results revealed differences in disease development between these regions and may be used to develop recommendations for a frequency of fungicide applications according to the regional risk of epidemics, leading to a significant reduction in fungicide use.

关键词： potato     late blight     Phytophthora infestans     yield losses     retrospective analysis     mathematical model    

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CLIMATE-CHANGE-INDUCED TEMPORAL VARIATION IN PRECIPITATION INCREASES NITROGEN LOSSES FROM INTENSIVE CROPPING

《农业科学与工程前沿（英文）》 2022年 第9卷 第3期   页码 457-464 doi: 10.15302/J-FASE-2022452

摘要：

● A simple model was used to evaluate how increasing temporal variability in precipitation influences crop yields and nitrogen losses.

关键词： crop yield     fertilizer timing     nitrogen loss     precipitation variability     toy model    

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Numerical study of conduction and radiation heat losses from vacuum annulus in parabolic trough receivers

Dongqiang LEI, Yucong REN, Zhifeng WANG

《能源前沿（英文）》 2022年 第16卷 第6期   页码 1048-1059 doi: 10.1007/s11708-020-0670-7

摘要： Parabolic trough receiver is a key component to convert solar energy into thermal energy in the parabolic trough solar system. The heat loss of the receiver has an important influence on the thermal efficiency and the operating cost of the power station. In this paper, conduction and radiation heat losses are analyzed respectively to identify the heat loss mechanism of the receiver. A 2-D heat transfer model is established by using the direct simulation Monte Carlo method for rarefied gas flow and heat transfer within the annulus of the receiver to predict the conduction heat loss caused by residual gases. The numerical results conform to the experimental results, and show the temperature of the glass envelope and heat loss for various conditions in detail. The effects of annulus pressure, gas species, temperature of heat transfer fluid, and annulus size on the conduction and radiation heat losses are systematically analyzed. Besides, the main factors that cause heat loss are analyzed, providing a theoretical basis for guiding the improvement of receiver, as well as the operation and maintenance strategy to reduce heat loss.

关键词： parabolic trough receiver     vacuum annulus     rarefied gas     DSMC (direct simulation Monte Carlo)     heat loss    

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NUTRIENT USE EFFICIENCY AND LOSSES OF INDUSTRIAL FARMS AND MIXED SMALLHOLDINGS: LESSONS FROM THE NORTH

Yifei MA, Ling ZHANG, Zhaohai BAI, Rongfeng JIANG, Yong HOU, Lin MA

《农业科学与工程前沿（英文）》 2021年 第8卷 第1期   页码 58-71 doi: 10.15302/J-FASE-2020371

摘要： The proportion of industrial livestock in China has increased over the past 30 years, which increases animal performance but causes the decoupling of crop and livestock production. Here, we aimed to quantify nutrient flows, nutrient use efficiency, and nutrient losses in different livestock systems in the North China Plain based on the NUFER-farm model. Activity data were collected by face-to-face surveys on pig and dairy (41 livestock farms) during 2016–2018. The two systems included industrial farms and mixed smallholdings. In mixed smallholdings, 4.0% and 9.6% of pig and dairy feed dry matter (DM) were derived from household farmland, but 4.8% and 9.3% of manure DM recycled to household farmland. Nutrient use efficiency in industrial farms was higher than in mixed smallholdings at animal level, herd level, and system level. To produce 1 kg N and P in animal products, nutrient losses in industrial pig farms (2.0 kg N and 1.3 kg P) were lower than in mixed pig smallholdings, nutrient losses in industrial dairy farms (2.7 kg N and 2.2 kg P) were slightly higher than in mixed dairy smallholdings. Liquid manure discharge in industrial farms was the main losses pathway in contrast to mixed smallholdings. This study suggests that feed localization can reduce nutrient surpluses at the district level. It is necessary to improve manure management and increase the degree of integrated crop-livestock in smallholdings. In industrial farms, it is desirable to increase the liquid manure recycling ratio through cooperating livestock and crop production at the district level.

关键词： industrial farms     mixed smallholdings     pig     dairy     nutrient management    

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Optimal Su-Do-Ku based interconnection scheme for increased power output from PV array under partial shading conditions

P. SRINIVASA RAO,P. DINESH,G. SARAVANA ILANGO,C. NAGAMANI

《能源前沿（英文）》 2015年 第9卷 第2期   页码 199-210 doi: 10.1007/s11708-015-0350-1

摘要： Partial shading is a common phenomenon in PV arrays. They drastically reduce the power output because of mismatch losses, which are reliant on the shape of the shade as well as the locations of shaded panels in the array. The power output can be improved by distributing the shade over various rows to maximize the current entering the node. A Su-Do-Ku configuration can be used to rearrange the physical locations of the PV modules in a total cross tied PV array with the electrical connections left unchanged. However, this arrangement increases the length of the wire required to interconnect the panels thus increasing the line losses. In this paper, an improved Su-Do-Ku arrangement that reduces the length of the wire required for the connection is proposed. The system is designed and simulated in a Matlab/Simulink environment for various shading patterns and the efficacies of various arrangements are compared. The results prove that the power output is higher in the proposed improved Su-Do-Ku reconfiguration technique compared to the earlier proposed Su-Do-Ku technique.

关键词： array configuration     mismatch losses     partial shading     line losses     Su-Do-Ku arrangement    

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Development and challenges of green food in China

Mahmood ul HASSAN, Xin WEN, Jiuliang XU, Jiahui ZHONG, Xuexian LI

《农业科学与工程前沿（英文）》 2020年 第7卷 第1期   页码 56-66 doi: 10.15302/J-FASE-2019296

摘要：

Green food in China refers to a wide array of primary and processed agricultural products that are safe, nutritious and of high quality for human consumption. Green food has been certified and produced following the principle of sustainability since the 1990s, making historic achievements in providing quality food, protecting the environment, increasing farmer income, and nurturing agricultural brands over the past 30 years in China. Today, the green food industry enters a steady-growth stage in terms of cultivation area, product number and sales. This article summarizes the history of the development of green food in China and current achievements, analyze major challenges that may hamper further development of the industry, and propose strategies to address these challenges, i.e., optimization of the food supply chain, deep food processing, and utilization of food wastes.

关键词： green food     food losses     storage     processing     transportation     sustainability    

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Review on drivers, trends and emerging issues of the food wastage in China

Lin MA,Wei QIN,Tara GARNETT,Fusuo ZHANG

《农业科学与工程前沿（英文）》 2015年 第2卷 第2期   页码 159-167 doi: 10.15302/J-FASE-2015066

摘要： China has successfully achieved food self-sufficiency over the past 50 years, however, with large inputs and losses. To meet the challenge of feeding a growing population with limited resources, many studies have explored options for improving productivity and efficiency of the food production. However, there have been few studies into the potential of reducing food loss along the whole food production-consumption chain. Here we review the literature on food waste in China. We briefly analyze (1) the drivers that influence levels of food waste in the food chain, (2) examine trends in the volumes and types of food wasted at different stages in the food chain, (3) assess the environmental and resource consequences of food waste in the food chain, and (4) evaluate the policy and stakeholder responses to the emerging challenges. It is concluded that reducing food loss and meeting food security in China requires a coherent institutional structure that promotes the synergistic outcomes of research, policy and education. Suggested key actions include (1) improving machinery and facility for sowing, harvesting, transportation and storage, which can reduce food loss by up to 50%, and (2) improving food waste recycling management, based on coupled food production and consumption systems.

关键词： food security     food chain     food wastes and losses     environmental impacts    

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Numerical study of internal flow field and flow passage improvement of an inlet particle separator

Florian PAOLI, Tong WANG

《能源前沿（英文）》 2011年 第5卷 第4期   页码 386-397 doi: 10.1007/s11708-011-0156-8

摘要： By performing gas flow field numerical simulations for several inlet Reynolds numbers (from 2 × 10 to 9 × 10 ) and byflow ratios (from 10% to 20%), the present study has proposed to improve the flow passage of an inlet particle separator. An adjacent objective of the study is to lower pressure losses of the inlet particle separator (IPS). No particle has been included in the gas flow for a -epsilon turbulence model. The velocity distribution in different sections and the pressure coefficient along the duct have been analyzed, which indicates that there exist important low-velocity regions and vortices in the separation area. Therefore, the profile of streamlines along the original passage has been considered. This profile illustrated a vacuum region in the same area. All investigations suggest that the separation area is the most critical one for fulfilling the objective on pressure losses limitation. Then the flow passage improvement method has focused on the separation area. An improved shape has been designed in order to suit smoothly to the streamlines in this region. Similar numerical studies as those for the original shape have been conducted on this improved shape, confirming some considerable enhancements compared with the original shape. The significant vortices which appear in the original shape reduce in amount and size. Besides, pressure losses are greatly decreased in both outlets (up to 30% for high Reynolds number) and the flow is uniform at the main outlet. Subsequent engineering surveys could rely on expressions obtained for in both outlets which extend the pressure losses for a wide range of inlet Reynolds numbers. As a result, the numerical calculations demonstrate that the flow passage improvement method applied in this study has succeeded in designing a shape which enhances the flow behavior.

关键词： streamlines     pressure losses     flow passage improvement     inlet particle separator (IPS)    

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用高光谱发光法研究Cu(Inx,Ga1–x)Se2 (CIGS)模块中由P1引起的功率损耗的成因 Article

César Omar Ramírez Quiroz, Laura-Isabelle Dion-Bertrand, Christoph J. Brabec, Joachim Müller, Kay Orgassa

《工程（英文）》 2020年 第6卷 第12期   页码 1395-1402 doi: 10.1016/j.eng.2019.12.019

摘要：

在本文中，我们利用了高光谱高分辨率光致发光映射技术，这是一个强大的工具，可用于选择和优化在Cu(Inx,Ga1-x)Se2（CIGS）模块上对子电池进行图案化互连的激光烧蚀工艺。通过这种方式，我们可以完成对消融区域附近材料降解的深度监测以及对潜在机制的识别。具体而言，通过分析在CIGS沉积之前烧蚀的标准P1图案线，我们发现了沿着下部的钼槽边缘的异常发射猝灭效应。通过扫描电子显微镜（SEM）比较了P1边缘的横截面的形貌，我们进一步合理化产生这种效应的起因，但无法用厚度变化解释光发射的减少。我们还研究了激光诱导对CIGS沉积后的P1图案线带来的损伤。然后，我们首次记录了短距离损坏区域，该区域与在激光路径上应用的光学孔径无关。我们的发现能更好地理解P1引起的功率损耗，并为改进与行业相关的模块互连方案提供了新的见解。

关键词： Cu(Inx     Ga1–x)Se2     电池到模块的效率差距     由P1引起的功率损耗     高光谱光致发光     激光烧蚀短程热效应    

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标题 作者 时间 类型 操作

Development of an analytical model to estimate the churning losses in high-speed axial piston pumps

期刊论文

NUTRIENT USE EFFICIENCY AND LOSSES OF INDUSTRIAL FARMS AND MIXED SMALLHOLDINGS: LESSONS FROM THE NORTH

期刊论文

HOTSPOTS OF NUTRIENT LOSSES TO AIR AND WATER: AN INTEGRATED MODELING APPROACH FOR EUROPEAN RIVER BASINS

期刊论文

GASEOUS REACTIVE NITROGEN LOSSES FROM ORCHARDS, VEGETABLES AND TEA PLANTATIONS

期刊论文

Exergy losses in premixed flames of dimethyl ether and hydrogen blends

Tongbin ZHAO, Jiabo ZHANG, Dehao JU, Zhen HUANG, Dong HAN

期刊论文

Test investigation on hydraulic losses in the discharge passage of an axial-flow pump

QIU Baoyun, CAO Haihong, JIANG Wei, GAO Zhaohui, WANG Fei

期刊论文

Development and testing of a weather-based model to determine potential yield losses caused by potato

Alexey FILIPPOV, Maria KUZNETSOVA, Alexander ROGOZHIN, Olga IAKUSHEVA, Valentina DEMIDOVA, Natalia STATSYUK

期刊论文

CLIMATE-CHANGE-INDUCED TEMPORAL VARIATION IN PRECIPITATION INCREASES NITROGEN LOSSES FROM INTENSIVE CROPPING

期刊论文

Numerical study of conduction and radiation heat losses from vacuum annulus in parabolic trough receivers

Dongqiang LEI, Yucong REN, Zhifeng WANG

期刊论文

NUTRIENT USE EFFICIENCY AND LOSSES OF INDUSTRIAL FARMS AND MIXED SMALLHOLDINGS: LESSONS FROM THE NORTH

Yifei MA, Ling ZHANG, Zhaohai BAI, Rongfeng JIANG, Yong HOU, Lin MA

期刊论文

Optimal Su-Do-Ku based interconnection scheme for increased power output from PV array under partial shading conditions

P. SRINIVASA RAO,P. DINESH,G. SARAVANA ILANGO,C. NAGAMANI

期刊论文

Development and challenges of green food in China

Mahmood ul HASSAN, Xin WEN, Jiuliang XU, Jiahui ZHONG, Xuexian LI

期刊论文

Review on drivers, trends and emerging issues of the food wastage in China

Lin MA,Wei QIN,Tara GARNETT,Fusuo ZHANG

期刊论文

Numerical study of internal flow field and flow passage improvement of an inlet particle separator

Florian PAOLI, Tong WANG

期刊论文

用高光谱发光法研究Cu(Inx,Ga1–x)Se2 (CIGS)模块中由P1引起的功率损耗的成因

César Omar Ramírez Quiroz, Laura-Isabelle Dion-Bertrand, Christoph J. Brabec, Joachim Müller, Kay Orgassa

期刊论文