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Impact of introducing a herb pasture area into a New Zealand sheep and beef hill country farm system:

Cécile DURANTON, Cory MATTHEW

《农业科学与工程前沿(英文)》 2018年 第5卷 第1期   页码 87-97 doi: 10.15302/J-FASE-2018202

摘要: New Zealand is well known for export of meat and dairy products from low cost pastoral systems. These farm systems are continually evolving for increased efficiency, in part through the use of metabolic energy modeling tools by farmers and farm consultants to explore alternative farm system configurations and identify new efficiencies. One recent innovation is the introduction of a herb pasture area, such as plantain. We used metabolic energy modeling to quantify seasonal feed flows in two successive years in a New Zealand hill country farm system, and to analyze the impact of the introduction of an area of plantain. Models employed were a self-built Microsoft Excel spreadsheet and a commercial New Zealand farm systems modeling package, FARMAX. Herbage production, animal performance and financial results for a base farm scenario created from the average of survey data for hill farms in the southern North Island, and the same farm with 10% and 20% of the area in plantain for the years 2010–2011 and 2011–2012 were modeled. The self-built model performed similarly to the commercial model. The system configuration of the base farm stockpiles surplus autumn feed for release to animals in winter and also incorporates flexibility that confers resilience to interannual weather variation through varying dates animals are purchased or sold. The introduction of an area of plantain was predicted to increase herbage production, animal performance and financial returns. The predicted benefit was higher for the year 2010–2011 where a drought occurred in summer than for the following year with higher summer rainfall. This demonstrates the profitability of introducing a plantain area to New Zealand hill farm systems, and suggests plantain will assist to mitigate adverse effects of warmer and drier summer conditions associated with current climate change trends.

关键词: farm system configuration     herb pasture     metabolic energy budgeting     plantain     sheep and beef farming    

Framework design of a hybrid energy system by combining wind farm with small gas turbine power plants

Nengsheng BAO, Weidou NI,

《能源前沿(英文)》 2010年 第4卷 第2期   页码 205-210 doi: 10.1007/s11708-009-0073-2

摘要: Owing to the stochastic characteristic of natural wind speed, the output fluctuation of wind farm has a negative impact on power grid when a large-scale wind farm is connected to a power grid. It is very difficult to overcome this impact only by wind farm itself. A novel power system called wind-gas turbine hybrid energy system was discussed, and the framework design of this hybrid energy system was presented in detail in this paper. The hybrid energy system combines wind farm with several small gas turbine power plants to form an integrated power station to provide a relatively firm output power. The small gas turbine power plant has such special advantages as fast start-up, shutdown, and quick load regulation to fit the requirement of the hybrid energy system. Therefore, the hybrid energy system uses the output from the small gas turbine power plants to compensate for the output fluctuation from the wind farm for the firm output from the whole power system. To put this hybrid energy system into practice, the framework must be designed first. The capacity of the wind farm is chosen according to the capacity and units of small gas turbine power plants, load requirement from power grid, and local wind energy resource distribution. Finally, a framework design case of hybrid energy system was suggested according to typical wind energy resource in Xinjiang Autonomous Region in China.

关键词: framework design     hybrid energy system     wind farm     gas turbine power plants    

深圳城市供水系统产权结构重组模式及评价

肖文,欧阳芳锐,王先甲

《中国工程科学》 2004年 第6卷 第7期   页码 48-52

摘要:

提出了城市供水系统产权结构重组的两种基本模式,运用制度经济学和管理学理论,提出产权结构模式评价的指标与方法,分析了这两种产权结构模式的特性和在这两种模式下不同利益主体的行为与利益关系的变化特点及优缺点,并提出了缓解劣势的手段与方法。

关键词: 城市供水     产权结构     产权重组     产权模式评价    

NEW ZEALAND DAIRY FARM SYSTEMS AND KEY ENVIRONMENTAL EFFECTS

《农业科学与工程前沿(英文)》 2021年 第8卷 第1期

摘要:

• NZ dairy farming systems are based on year-round grazing of perennial pasture (ryegrass/white clover).

• Milk production per hectare has increased by about 29% with increased use of externally-sourced feeds over the last two decades.

• Externally-sourced feeds with a low protein concentration can potentially reduce N2O emissions and N leaching per unit of production.

• Systems analysis is important for evaluating mitigations to minimize trade-offs between environmental impacts.

 

This paper provides an overview of the range of dairy pasture grazing systems used in New Zealand (NZ), the changes with increased inputs over time and associated key environmental effects including nitrogen (N) leaching and greenhouse gas (GHG) emissions. NZ dairy farming systems are based on year-round grazing and seasonal milk production on perennial ryegrass/clover pasture where cows are rotationally grazed in paddocks. There was an increase in stocking rate on NZ dairy farms from 2.62 cows ha1 in 2000/2001 to 2.84 cows ha1 in 2015/2016. During the same period annual milk solids production increased from 315 to 378 kg·yrper cow. This performance has coincided with an increase in N fertilizer use (by ~ 30%) and a twofold increase in externally-sourced feeds. Externally-sourced feeds with a low protein concentration (e.g., maize silage) can increase the efficiency of N utilization and potentially reduce N losses per unit of production. Off-paddock facilities (such as standoff or feed pads) are often used to restrict grazing during very wet winter conditions. A systems analysis of contrasting dairy farms in Waikato (largest NZ dairying region) indicates that the increased input would result in an increase in per-cow milk production but little change in efficiency of milk production from a total land use perspective. This analysis also shows that the increased inputs caused an 11% decrease in N footprint (i.e., N emissions per unit of milk production) and a 2% increase in C footprint (i.e., greenhouse gas (GHG) emissions per unit of milk production).jiafa.luo@agresearch.co.nz

NEW ZEALAND DAIRY FARM SYSTEMS AND KEY ENVIRONMENTAL EFFECTS

Jiafa LUO, Stewart LEDGARD

《农业科学与工程前沿(英文)》 2021年 第8卷 第1期   页码 148-158 doi: 10.15302/J-FASE-2020372

摘要: This paper provides an overview of the range of dairy pasture grazing systems used in New Zealand (NZ), the changes with increased inputs over time and associated key environmental effects including nitrogen (N) leaching and greenhouse gas (GHG) emissions. NZ dairy farming systems are based on year-round grazing and seasonal milk production on perennial ryegrass/clover pasture where cows are rotationally grazed in paddocks. There was an increase in stocking rate on NZ dairy farms from 2.62 cows ha in 2000/2001 to 2.85 cows ha in 2015/2016. During the same period annual milk solids production increased from 315 to 378 kg·yr per cow. This performance has coincided with an increase in N fertilizer use (by 30%) and a twofold increase in externally-sourced feeds. Externally-sourced feeds with a low protein concentration (e.g., maize silage) can increase the efficiency of N utilization and potentially reduce N losses per unit of production. Off-paddock facilities (such as standoff or feed pads) are often used to restrict grazing during very wet winter conditions. A systems analysis of contrasting dairy farms in Waikato (largest NZ dairying region) indicates that the increased input would result in an increase in per-cow milk production but little change in efficiency of milk production from a total land use perspective. This analysis also shows that the increased inputs caused an 11% decrease in N footprint (i.e., N emissions per unit of milk production) and a 2% increase in C footprint (i.e., greenhouse gas (GHG) emissions per unit of milk production).

关键词: dairy farms     environmental impacts     grazing systems     intensification     mitigation    

considerations for redesigning sustainable cropping systems: the value of data-mining large and detailed farmdata sets at the cropping system level

Nicolas MUNIER-JOLAIN, Martin LECHENET

《农业科学与工程前沿(英文)》 2020年 第7卷 第1期   页码 21-27 doi: 10.15302/J-FASE-2019292

摘要:

Redesigning cropping and farming systems to enhance their sustainability is mainly addressed in scientific studies using experimental and modeling approaches. Large data sets collected from real farms allow for the development of innovative methods to produce generic knowledge. Data mining methods allow for the diversity of systems to be considered holistically and can take into account the diversity of production contexts to produce site-specific results. Based on the very few known studies using such methods to analyze the crop management strategies affecting pesticide use and their effect on farm performance, we advocate further investment in the development of large data sets that can support future research programs on farming system design.

关键词: data mining     holistic     Integrated Pest Management     economics     DEPHY network.    

Effects of green roof damping and configuration on structural seismic response

《结构与土木工程前沿(英文)》   页码 1133-1144 doi: 10.1007/s11709-023-0959-9

摘要: Sustainable structures are critical for addressing global climate change. Hence, their structural resilience or ability to recover from natural events must be considered comprehensively. Green roofs are a widely used sustainable feature that improve the environment while providing excellent occupant amenity. To expand their usage, their inherent damping and layout sensitivity to seismic performance are investigated in this study. The soil of a green roof can serve as a damper to dissipate the energy generated by earthquakes or other dynamic events. Results of preliminary analysis show that a green roof soil can increase localized damping by 2.5% under both dry and saturated conditions. Based on these findings, nonlinear time-history analyses are conducted on a three-story building in SAP2000 to monitor the structural behavior with and without a green roof. The increased damping in the green roof soil is beneficial to the structural performance, i.e., it reduces the building displacement and acceleration by 10% and 12%, respectively. Additionally, certain configurations are more effective and beneficial to the structural response than others, which suggests the possibility of design optimization. Based on the findings of this study, new methods of modeling and considering green roofs in structural design are established.

关键词: green infrastructure     green roof     structural resilience     seismic design    

Network-based optimization techniques for wind farm location decisions

Jorge Ignacio CISNEROS-SALDANA, Seyedmohammadhossein HOSSEINIAN, Sergiy BUTENKO

《工程管理前沿(英文)》 2018年 第5卷 第4期   页码 533-540 doi: 10.15302/J-FEM-2018025

摘要:

This study aims to find appropriate locations for wind farms that can maximize the overall energy output while controlling the effects of wind speed variability. High wind speeds are required to obtain the maximum possible power output of a wind farm. However, balancing the wind energy supplies over time by selecting diverse locations is necessary. These issues are addressed using network-based models. Hence, actual wind speed data are utilized to demonstrate the advantages of the proposed approach.

关键词: wind energy     wind farm location     network analysis     optimization     clique     s-plex    

Energy storage resources management: Planning, operation, and business model

《工程管理前沿(英文)》   页码 373-391 doi: 10.1007/s42524-022-0194-4

摘要: With the acceleration of supply-side renewable energy penetration rate and the increasingly diversified and complex demand-side loads, how to maintain the stable, reliable, and efficient operation of the power system has become a challenging issue requiring investigation. One of the feasible solutions is deploying the energy storage system (ESS) to integrate with the energy system to stabilize it. However, considering the costs and the input/output characteristics of ESS, both the initial configuration process and the actual operation process require efficient management. This study presents a comprehensive review of managing ESS from the perspectives of planning, operation, and business model. First of all, in terms of planning and configuration, it is investigated from capacity planning, location planning, as well as capacity and location combined planning. This process is generally the first step in deploying ESS. Then, it explores operation management of ESS from the perspectives of state assessment and operation optimization. The so-called state assessment refers to the assessment of three aspects: The state of charge (SOC), the state of health (SOH), and the remaining useful life (RUL). The operation optimization includes ESS operation strategy optimization and joint operation optimization. Finally, it discusses the business models of ESS. Traditional business models involve ancillary services and load transfer, while emerging business models include electric vehicle (EV) as energy storage and shared energy storage.

关键词: energy storage system     energy storage resources management     planning configuration     operational management     business model    

Tianrun Xia County phase III 99.5 MW wind power engineering technology and green innovation

Xiaobo WANG

《工程管理前沿(英文)》 2019年 第6卷 第1期   页码 131-137 doi: 10.1007/s42524-019-0012-9

摘要:

关键词: low carbon design     green standard system     environmental protection     sustainable development     Tianrun Sijiao Town wind farm    

Effect of cutterhead configuration on tunnel face stability during shield machine maintenance outages

《结构与土木工程前沿(英文)》 2023年 第17卷 第4期   页码 522-532 doi: 10.1007/s11709-023-0930-9

摘要: Owing to long-distance advancement or obstacles, shield tunneling machines are typically shut down for maintenance. Engineering safety during maintenance outages is determined by the stability of the tunnel face. Pressure maintenance openings are typically used under complicated hydrogeological conditions. The tunnel face is supported by a medium at the bottom of the excavation chamber and compressed air at the top. Owing to the high risk of face failure, the necessity of support pressure when cutterhead support is implemented and a method for determining the value of compressed air pressure using different support ratios must to be determined. In this study, a non-fully chamber supported rotational failure model considering cutterhead support is developed based on the upper-bound theorem of limit analysis. Numerical simulation is conducted to verify the accuracy of the proposed model. The results indicate that appropriately increasing the specific gravity of the supporting medium can reduce the risk of collapse. The required compressed air pressure increases significantly as the support ratio decreases. Disregarding the supporting effect of the cutterhead will result in a tunnel face with underestimated stability. To satisfy the requirement of chamber openings at atmospheric pressure, the stratum reinforcement strength and range at the shield end are provided based on different cutterhead aperture ratios.

关键词: tunnel face stability     cutterhead configuration     aperture ratio     pressure gradient     support ratio    

Optimizing the configuration of a clearwell by integrating pilot and full-scale tracer testing

LIU Wenjun, DU Zhipeng, JIN Junwei

《环境科学与工程前沿(英文)》 2007年 第1卷 第3期   页码 270-275 doi: 10.1007/s11783-007-0045-x

摘要: In this paper, the main factors impacting the plug flow pattern of a clearwell were investigated by integrating pilot-scale, full-scale clearwell tracer testing and computational fluid dynamics (CFD) simulation. It was found that pilot tracer testing, full-scale tracer testing and CFD simulation all demonstrated that the correlation between the ratio of / and can be approximately expressed by: / = 0.189 4ln()-0.049 4. This study confirmed that the installation of baffles within clearwells is an efficient way to optimize their configuration. In addition, the inlet velocity has a minimal contribution to the ratio of /. However, the ratio of turning channel width to channel width () significantly contributes to the ratio of/. The optimal ratio of is 0.8–1.2 for maintaining better plug flow pattern. The number of turning channels is one of the main factors that impact the ratio of /. When increasing the number of turning channels, a lower ratio of / is obtained.

Manufacturing system modeling and performance evaluation based on improved stochastic statechart

ZHANG Guojun, HE Jiabing, ZHU Haiping, CHEN Xuan

《机械工程前沿(英文)》 2007年 第2卷 第4期   页码 453-458 doi: 10.1007/s11465-007-0078-7

摘要: Stochastic statecharts are widely used in modeling systems. Considering that the comparability between different subsystems can streamline the modeling process, a stochastic statechart is improved by using the abstract sub-system and general system chart to express the comparability and integrity of a stochastic statechart respectively. Per formance data can be obtained by using a continuous-time Markov chain, which is transformed from a manufacturing system model described by the improved stochastic statechart. The case study shows that the improved stochastic statechart can effectively simplify the modeling and performance evaluation process and the results are useful to the configuration and optimization of a manufacturing system.

关键词: performance evaluation     different     configuration     improved     continuous-time    

基础冲刷对海上风电场塔架支撑系统动力特性的影响分析

严根华,古华,陆忠民,林毅峰

《中国工程科学》 2011年 第13卷 第1期   页码 69-73

摘要:

针对海上风力机塔柱支撑结构受到土基、海洋流体的复杂作用的特点,建立三维有限元数值模型,开展不同海床冲刷深度条件下支撑系统结构的动态特性,探讨其变化规律,为海上风力机支撑系统的动力稳定设计提供科学依据。

关键词: 冲刷     海上风电场     支撑系统     动力特性     三维有限元    

Tracing the impact of stack configuration on interface resistances in reverse electrodialysis by in situ

《环境科学与工程前沿(英文)》 2022年 第16卷 第4期 doi: 10.1007/s11783-021-1480-9

摘要:

• RED performance and stack resistance were studied by EIS and LSV.

关键词: Reverse electrodialysis     Electrochemical impedance spectroscopy     Concentration polarization     Spacer shadow effect    

标题 作者 时间 类型 操作

Impact of introducing a herb pasture area into a New Zealand sheep and beef hill country farm system:

Cécile DURANTON, Cory MATTHEW

期刊论文

Framework design of a hybrid energy system by combining wind farm with small gas turbine power plants

Nengsheng BAO, Weidou NI,

期刊论文

深圳城市供水系统产权结构重组模式及评价

肖文,欧阳芳锐,王先甲

期刊论文

NEW ZEALAND DAIRY FARM SYSTEMS AND KEY ENVIRONMENTAL EFFECTS

期刊论文

NEW ZEALAND DAIRY FARM SYSTEMS AND KEY ENVIRONMENTAL EFFECTS

Jiafa LUO, Stewart LEDGARD

期刊论文

considerations for redesigning sustainable cropping systems: the value of data-mining large and detailed farmdata sets at the cropping system level

Nicolas MUNIER-JOLAIN, Martin LECHENET

期刊论文

Effects of green roof damping and configuration on structural seismic response

期刊论文

Network-based optimization techniques for wind farm location decisions

Jorge Ignacio CISNEROS-SALDANA, Seyedmohammadhossein HOSSEINIAN, Sergiy BUTENKO

期刊论文

Energy storage resources management: Planning, operation, and business model

期刊论文

Tianrun Xia County phase III 99.5 MW wind power engineering technology and green innovation

Xiaobo WANG

期刊论文

Effect of cutterhead configuration on tunnel face stability during shield machine maintenance outages

期刊论文

Optimizing the configuration of a clearwell by integrating pilot and full-scale tracer testing

LIU Wenjun, DU Zhipeng, JIN Junwei

期刊论文

Manufacturing system modeling and performance evaluation based on improved stochastic statechart

ZHANG Guojun, HE Jiabing, ZHU Haiping, CHEN Xuan

期刊论文

基础冲刷对海上风电场塔架支撑系统动力特性的影响分析

严根华,古华,陆忠民,林毅峰

期刊论文

Tracing the impact of stack configuration on interface resistances in reverse electrodialysis by in situ

期刊论文