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Global patterns in above-ground net primary production and precipitation-use efficiency in grasslands 被引量:5
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作者 QIN Xiao-jing HONG Jiang-tao +1 位作者 MA Xing-xing WANG Xiao-dan 《Journal of Mountain Science》 SCIE CSCD 2018年第8期1682-1692,共11页
The above-ground net primary production(ANPP) and the precipitation-use efficiency(PUE) regulate the carbon and water cycles in grassland ecosystems, but the relationships among the ANPP, PUE and precipitation are sti... The above-ground net primary production(ANPP) and the precipitation-use efficiency(PUE) regulate the carbon and water cycles in grassland ecosystems, but the relationships among the ANPP, PUE and precipitation are still controversial. We selected 717 grassland sites with ANPP and mean annual precipitation(MAP) data from 40 publications to characterize the relationships ANPP–MAP and PUE–MAP across different grassland types. The MAP and ANPP showed large variations across all grassland types, ranging from 69 to 2335 mm and 4.3 to 1706 g m^(-2), respectively. The global maximum PUE ranged from 0.19 to 1.49 g m^(-2) mm^(-1) with a unimodal pattern. Analysis using the sigmoid function explained the ANPP–MAP relationship best at the global scale. The gradient of the ANPP–MAP graph was small for arid and semi-arid sites(MAP <400 mm). This study improves our understanding of the relationship between ANPP and MAP across dry grassland ecosystems. It provides new perspectives on the prediction and modeling of variations in the ANPP for different grassland types along precipitation gradients. 展开更多
关键词 Litter decomposition Alpine communities Tea bag index Carbon cycle Above-ground net primary production Precipitation-use efficiency Sigmoid function Precipitation gradients
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The study of metal cycles in China 被引量:2
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作者 Lu Zhongwu Yue Qiang 《Engineering Sciences》 EI 2010年第2期2-8,共7页
A model of Fe-flow in the life cycle of steel product was put forward and analyzed. Three important resource and environmental indicators for Fe-flow analysis,that is,steel scrap index,iron ore index and iron loss ind... A model of Fe-flow in the life cycle of steel product was put forward and analyzed. Three important resource and environmental indicators for Fe-flow analysis,that is,steel scrap index,iron ore index and iron loss index were derived from this model. Illustrative examples,demonstrating the influence of the variation of steel output on steel scrap index and iron ore index were given. Case studies for estimating the values of steel scrap index of Japan,China and USA in the period of 1988-1997 were carried out. It was clarified that the main reason of severe deficiency in steel scraps for China's steel industry was its continued rapid growth. The study of iron,copper,zinc and lead cycle in China was carried out successfully according to this model. 展开更多
关键词 model of Fe-flow in the life cycle of steel product steel scrap index iron ore index iron loss index variation of steel output metal cycles
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Concept of Integrated Waste Management as Recoverable Resources in Product Cycle
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作者 Aleksandr Telizhenko Vadym Lukianykhin +4 位作者 Sergey Kuzmenko Elena Lukianykhina Elena Vishnitskaya Min Li Tatyana Shevchenko 《Journal of Environmental Science and Engineering(B)》 2012年第3期312-323,共12页
This paper presents a conceptual framework of integrated waste management which focuses on all stages of product life cycle. A mechanism of resource recovery motivating from waste in economic system (designers, produ... This paper presents a conceptual framework of integrated waste management which focuses on all stages of product life cycle. A mechanism of resource recovery motivating from waste in economic system (designers, producers, consumers, stakeholders in the field of disposal of the product) is suggested. The classification of institutional and economic instruments in the field of waste management as recoverable resources is developed. The author has proposed a scientific and methodical approach to the formation of an integrated waste management as recoverable resources, which is based on a set of methods of economic incentives at all stages of product life cycle and ensures the maximum possible and the environmentally safe management of wastes containing valuable resource components. 展开更多
关键词 WASTE recoverable resources integrated waste management product life cycle organizational-economic mechanism.
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Identifying and Tracing Single Products During Their Entire Life Cycle Through Networked Manufacturing System
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作者 Saeed A. Mousa 《Management Studies》 2017年第6期502-507,共6页
This study covers the problem that most products become less competitive especially in the decline stages of their life cycle as most companies do not put adequate emphasis on using networked manufacturing systems in ... This study covers the problem that most products become less competitive especially in the decline stages of their life cycle as most companies do not put adequate emphasis on using networked manufacturing systems in the entire life cycle of a single product. The study employed a non-experimental approach to collect data. The research paper relied on secondary data for further analysis. The secondary sources used in this paper have been referenced progressively in the entire paper. The paper found that most companies are often faced with the challenge of coping with quality management in a product life cycle. Also, it found that networked manufacturing systems have provided a new paradigm for real-time monitoring and control at various life stages. The paper is divided as following parts: section 1 is about the background and problem statement. Section 2 comes through literature review including theoretical & empirical review. Section 3 explains the procedures and methods that were used in carrying out the study. It explains how data collection was carried out and how data analysis was performed. Section 4 is about the results the paper found. Section 5 is a discussion of the results presented. 展开更多
关键词 networked manufacturing product life cycle potential of market growth industrial automation
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A Study of the Bullwhip Effect for Short Life Cycle Products in Supply Chain Management
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作者 CAO Yong-hui LI Hui 《International Journal of Plant Engineering and Management》 2009年第2期65-69,共5页
Shorter product life cycles present new dressed in supply chain literature. This research challenges to managing production and logistics not adequately adaddresses issues pertaining to the management of supply chains... Shorter product life cycles present new dressed in supply chain literature. This research challenges to managing production and logistics not adequately adaddresses issues pertaining to the management of supply chains in a short life cycle environment. In this paper, we study the short life cycle environment; then we develop the ventory policy of the indirect manufacturer by explicitly using his demand us an output of the retailer's optimal inoptimal ordering policy. Finally, we also provide causes of the bullwhip effect in the context of short life cycle products. 展开更多
关键词 bullwhip effect short life cycle products supply chains
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基于TLBO算法的不确定性条件下复杂产品协同设计的可靠性拓扑优化 被引量:1
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作者 Zhaoxi Hong Xiangyu Jiang +2 位作者 冯毅雄 Qinyu Tian 谭建荣 《Engineering》 SCIE EI CAS CSCD 2023年第3期71-81,共11页
复杂产品的拓扑优化设计可以显著节省材料和节能,有效地降低惯性力和机械振动。本研究以一种大吨位液压机作为典型的复杂产品,用于阐述该优化方法。本文提出了一种基于可靠性与优化解耦模型和基于教学学习的优化(TLBO)算法的可靠性拓扑... 复杂产品的拓扑优化设计可以显著节省材料和节能,有效地降低惯性力和机械振动。本研究以一种大吨位液压机作为典型的复杂产品,用于阐述该优化方法。本文提出了一种基于可靠性与优化解耦模型和基于教学学习的优化(TLBO)算法的可靠性拓扑优化方法。将由板结构形成的支撑物作为拓扑优化对象,重量轻、稳定性好。将不确定性下的可靠性优化和结构拓扑优化协同处理。首先,利用有限差分法将优化问题中的不确定性参数修正为确定性参数。然后,将不确定性可靠性分析和拓扑优化的复杂嵌套解耦。最后,利用TLBO算法求解解耦模型,该算法参数少,求解速度快。TLBO算法采用了自适应教学因子,在初始阶段实现了更快的收敛速度,并在后期进行了更精细的搜索。本文给出了一个液压机基板结构的数值实例,说明了该方法的有效性。 展开更多
关键词 Plates structure Reliability Collaborative topology optimization Teaching-learning-based optimization algorithm UNCERTAINTY Collaborative design for product life cycle
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Removal of the main inflorescence to induce reflowering of loquat 被引量:2
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作者 Jiangrong Peng Wenkun Li +7 位作者 Yuan Yuan Zhiqiang Han Yunpeng Cao Muhammad Qasim Shahid Zhike Zhang Yongshun Gao Shunquan Lin Yuanyuan Jiang 《Horticultural Plant Journal》 SCIE CSCD 2022年第1期35-43,共9页
Loquat(Eriobotrya japonica Lindl.)is an evergreen fruit tree species of the Rosaceae,and its unique flowering time greatly hinders its production.To explore the artificial regulation of loquat flowering time,we remove... Loquat(Eriobotrya japonica Lindl.)is an evergreen fruit tree species of the Rosaceae,and its unique flowering time greatly hinders its production.To explore the artificial regulation of loquat flowering time,we removed the main inflorescence(by cutting it)to induce reflowering.For different loquat tree cultivars with different stages,the inflorescence was removed by cutting the main floral axis at two alternative positions:the upper or the lower position beneath the inflorescence,and it was found that the proportion of reflowering resulting from removing the upper position of the main floral axis of yellow-flesh loquat cultivars during the full-bloom stage was the highest.In addition,compared with those of the normal-growing panicles,the number of flower buds and branch axes of the reflowering panicles decreased significantly after cutting.Importantly,these newly produced inflorescences flowered 2–4 months later than normal-growing inflorescences did,effectively prolonging both the flowering and fruiting time.In addition,qRT-PCR results showed that EjFT1,EjFT2,EjAP1–1 and EjAP1–2 were highly expressed in the floral axis.These findings highlighted a new method for extending the production cycle of loquat and provided a reference for the flowering regulation of loquat and other economically important fruit tree species. 展开更多
关键词 Eriobotrya japonica Reflowering Flowering time CUTTING production cycle
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An Analysis of Contemporary Copper Recycling in China 被引量:9
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作者 岳强 陆钟武 《过程工程学报》 CAS CSCD 北大核心 2006年第4期683-690,共8页
Copper consumption increased very quickly in China in recent years,which could not be met by inland copper industry.In order to achieve a sustainable development of copper industry,an analysis of copper recycling in C... Copper consumption increased very quickly in China in recent years,which could not be met by inland copper industry.In order to achieve a sustainable development of copper industry,an analysis of copper recycling in China was necessary.For the life cycle of copper products a copper-flow diagram with time factor was worked out and the contemporary copper recycling in China was analyzed,from which the following data were obtained.The average life cycle of copper products was 30 years.From 1998 to 2002,the use ratio of copper scraps in copper production,the use ratio of copper scraps in copper manufacture,the materials self-support ratio in copper production,and the materials self-support ratio in copper manufacture were 26.50%,15.49%,48.05% and 59.41%,respectively.The materials self-support ratios in copper production and manufacture declined year by year in recent years on the whole,and the latter dropped more quickly.The average index of copper ore and copper scrap from 1998 to 2002 were 0.8475 t/t and 0.0736 t/t,respectively;and copper resource efficiency was 1.1855 t/t.Some efforts should be paid to reduce copper ores consumption and promote copper scraps regeneration.Copper scraps were mostly imported from foreign countries because of shortage in recent years in China.Here the reasons related to copper scraps deficiency were also demonstrated.But we can forecast:when copper production was in a slow rise or in a steady state in China,the deficiency of copper scraps may be mitigated;when copper production was in a steady state for a very long time,copper scraps may become relatively abundant.According to the status of copper industry in China,the raw materials of copper production and manufacture have to depend on oversea markets heavily in recent years,and at the same time,the copper scraps using proportion and efficiency in copper industry should be improved. 展开更多
关键词 copper scrap copper recycling copper-flow diagram of the life cycle of copper products self-support ratio copper ore index copper scrap index copper resource efficiency
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Two Approaches of Substance Flow Analysis—An Inspiration from Fluid Mechanics 被引量:2
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作者 Lu Zhongwu 《Engineering Sciences》 EI 2008年第1期2-8,共7页
That flow is the common feature of substance flow and fluid flow is the viewpoint emphasized in the paper. Some notes on fluid mechanics, including the two approaches of fluid flow description, were given. The concept... That flow is the common feature of substance flow and fluid flow is the viewpoint emphasized in the paper. Some notes on fluid mechanics, including the two approaches of fluid flow description, were given. The concepts of the chain and the chain group of product life cycles, which are essential for understanding the specific features of substance flow, were advanced. Taking the specific feature of substance flow into consideration, on the analogy of the two approaches in fluid mechanics, two approaches of substance flow analysis, i.e. L method and E model, were formulated. Illustrative models of steady and unsteady substance flow were sketched by both methods, and comparison between them was made in general. 展开更多
关键词 Lagran gian and Eulerian approaches of fluid flow description the chain of product life cycles the chaingroup of product life cycles the L approach of substance flow analysis the E approach of substance flow analysis steady and unsteady substance flow
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Optimization of post-warranty sequential inspection for second-hand products 被引量:1
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作者 Dae-Kyung Kim Jae-Hak Lim Dong Ho Park 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2017年第4期793-800,共8页
This paper considers an optimal sequential inspection schedule for a second-hand product after that the free nonrenewable warranty is expired. The length of warranty is prespecified and during the warranty period, the... This paper considers an optimal sequential inspection schedule for a second-hand product after that the free nonrenewable warranty is expired. The length of warranty is prespecified and during the warranty period, the product is minimally repaired by the dealer when it fails. Following the expiration of the non-renewing warranty, the product is inspected and upgraded sequentially a fixed number of times at the expenses of the customer.At each inspection, the failure rate of the product is reduced proportionally so that the product is upgraded. The product is assumed to deteriorate as it ages and the replacement of the product occurs when a fixed number of inspections are rendered. In addition,the intervals between two successive inspections are assumed to decrease monotonically. The main objective of this paper is to determine the optimal improvement level to upgrade the product at each inspection so that the expected maintenance cost during the life cycle of the product is minimized from the perspective of the customer. Under the given cost structures, we derive an explicit formula to obtain the expected maintenance cost incurred during the life cycle of the product and discuss the method to find the optimal level of the improvement analytically in case the failure times follow the Weibull distribution. Numerical results are analyzed to observe the impact of relevant parameters on the optimal solution. 展开更多
关键词 second-hand product sequential inspection upgrade action life cycle of the product expected maintenance cost free non-renewable warranty
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A Cost-benefit Measuring Model of Green Products in Manufacturing Industry 被引量:1
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作者 Qingshan Zhang Luping Zhang 《Chinese Business Review》 2005年第5期8-15,共8页
The paper builds up a cost-benefit measuring model of green products in manufacturing industry throughout its full life cycle, which can quantify green products' cost and benefit completely and correctly under the ci... The paper builds up a cost-benefit measuring model of green products in manufacturing industry throughout its full life cycle, which can quantify green products' cost and benefit completely and correctly under the circumstance of satisfying enterprise, customer, environment and society. It also puts forth an operable method to estimate social benefit by opportunity cost and establishes a profit maximization-programming model. The model can be applied to justify whether some kinds of green products should be developed and produced. 展开更多
关键词 green product full life cycle social benefit estimation the measuring model
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INTELLIGENT MECHANISM TO SUPPORT DFX ABILITIES IN AUTOMATED DESIGNER'S ENVIRONMENT
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作者 乌兰木其 邓家堤 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2000年第4期234-241,共6页
The paper aims at providing a computerized design environment to support product design practically. The authors solved this problem by taking the product life-cycle issues into consideration as more as possible durin... The paper aims at providing a computerized design environment to support product design practically. The authors solved this problem by taking the product life-cycle issues into consideration as more as possible during the design process from the designer-oriented perspective of view. Design for X-abilities (DFX) is an effective approach to this philosophy. So the paper mainly presents the infrastructure of an intelligent DFX mechanism which is the essential part of the developed product design environment. At first the designer-oriented computer environment DesignerSpace is introduced for understanding the designer how to implement design activities and DFX method better. In order to integrate design knowledge from downstream aspects for the optimization and the design decision-making, an intelligent DFX mechanism is developed to incorporate knowledge base, algorithm-base and monitoring/debugging tools. DesignerSpace is implemented with DFX abilities and applied to the blisk design of aircraft engine and the further development is strongly intended. 展开更多
关键词 product design product life cycle designer-oriented environment intelligent mechanism design knowledge information infrastructure
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Product Family Design Methodology Using Object-Oriented Approach
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作者 WANG Ai-min, MENG Ming-chen, HUANG Jing-yuan (Department. of Precision Instruments and Mechanology, Tsinghua Univers ity, Beijing 100084, China) 《厦门大学学报(自然科学版)》 CAS CSCD 北大核心 2002年第S1期141-142,共2页
The serious competition environment of global marke t requests the enterprise to change traditional product development strategy and a dopt new theory in order to meet diverse customer needs while maintaining near m a... The serious competition environment of global marke t requests the enterprise to change traditional product development strategy and a dopt new theory in order to meet diverse customer needs while maintaining near m ass production efficiency, which is the main philosophy of mass customization. P roduct family design is research focus at present and also is the core technolog y of DFMC (design for mass customization). Firstly, this paper explores the fund amental issues of product family, such as concepts of modularity, commonality/di versity, product platform and product family architecture etc. We compare the te rminology between product family and object-oriented approach in the next step. Thirdly, this paper puts forwards one product family design methodology based o n product platform and under different phase of product life cycle constrains, f or example, functional, assembly and service etc. At the end section of this pap er, we applied, the object-oriented approach in above mentioned product family design methodology to realize the design process. In one word, this paper propos ed one product family design methodology based on object oriented approach and p roduct life cycle consideration, especially the conjointness of characteristic o f OOA and concepts of product family. The main property of OOA are encapsulation , inherence and polymorphism. Encapsulation can represent the module or building blocks of product family. Inherence can be extended to describe the modularity and commonality, and also be used to construct variant space. Alternative specif ic of product family architecture can be embodied with polymorphism. And fin aly, we give the future work contents. In order to derive the product platform a nd achieve modularity and commonality/diversity, interface management between bu ilding block is necessary. The question is how the OOA can be applied in interfa ce management to get our aim OOA is the basis of many information management sy stem, then the question is how to build one system to manage the information of product family and support mass customization The third question is how to deve lop one computer aided tool to facilitate the application of OOA for product fam ily design, even be used to category of design for mass customization. 展开更多
关键词 product family design product platform object- oriented approach (OOA) product life cycle
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A Model Fitting Approach to Depict the Global Textile Trade
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作者 区健勋 陈若瀚 《Journal of Donghua University(English Edition)》 EI CAS 2004年第1期121-127,共7页
Since the mercantilism era, economists have built up trade theories to explain the rationale and patterns of world trade.In this paper, the explanatory power of the international product life cycle (IPLC) theory for d... Since the mercantilism era, economists have built up trade theories to explain the rationale and patterns of world trade.In this paper, the explanatory power of the international product life cycle (IPLC) theory for describing the trends and patterns of the global textile trade, one of the most geographically dispersed export items in both developed and developing countries/regions, is discussed. Data at SITC two-digit level (SITC 65 ) were collected and time series regressions were performed to analyze the value trends and world shares of textile exports from 1990 to 2000 for selected developed economies. It was found that some developed economies have increased their world shares in textile exports, which indicated that global trade shift in the textile industry may not follow what the IPLC has suggested. 展开更多
关键词 Textile trade International product life cycle Developed and developing economies Trading pattern
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Full Friendly Index Sets of Cartesian Products of Two Cycles 被引量:3
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作者 Wai chee SHIU 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2010年第7期1233-1244,共12页
Let G =(V, E) be a connected simple graph. A labeling f : V → Z2 induces an edge labeling f* : E → Z2 defined by f*(xy) = f(x) +f(y) for each xy ∈ E. For i ∈ Z2, let vf(i) = |f^-1(i)| and ef(i... Let G =(V, E) be a connected simple graph. A labeling f : V → Z2 induces an edge labeling f* : E → Z2 defined by f*(xy) = f(x) +f(y) for each xy ∈ E. For i ∈ Z2, let vf(i) = |f^-1(i)| and ef(i) = |f*^-1(i)|. A labeling f is called friendly if |vf(1) - vf(0)| ≤ 1. For a friendly labeling f of a graph G, we define the friendly index of G under f by if(G) = e(1) - el(0). The set [if(G) | f is a friendly labeling of G} is called the full friendly index set of G, denoted by FFI(G). In this paper, we will determine the full friendly index set of every Cartesian product of two cycles. 展开更多
关键词 vertex labeling friendly labeling friendly index set Cartesian product of two cycles
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L(j,k)-number of Direct Product of Path and Cycle 被引量:6
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作者 Wai Chee SHIU Qiong WU 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2013年第8期1437-1448,共12页
For positive numbers j and k, an L(j,k)-labeling f of G is an assignment of numbers to vertices of G such that |f(u)-f(v)|≥j if uv∈E(G), and |f(u)-f(v)|≥k if d(u,v)=2. Then the span of f is the di... For positive numbers j and k, an L(j,k)-labeling f of G is an assignment of numbers to vertices of G such that |f(u)-f(v)|≥j if uv∈E(G), and |f(u)-f(v)|≥k if d(u,v)=2. Then the span of f is the difference between the maximum and the minimum numbers assigned by f. The L(j,k)-number of G, denoted by λj,k(G), is the minimum span over all L(j,k)-labelings of G. In this paper, we give some results about the L(j,k)-number of the direct product of a path and a cycle for j≤k. 展开更多
关键词 L(j k)-labeling product of a path and a cycle
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On the role of the tricarboxylic acid cycle in plant productivity 被引量:4
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作者 Youjun Zhang Alisdair R.Fernie 《Journal of Integrative Plant Biology》 SCIE CAS CSCD 2018年第12期1199-1216,共18页
The tricarboxylic acid(TCA) cycle is one of the canonical energy pathways of living systems, as well as being an example of a pathway in which dynamic enzyme assemblies, or metabolons, are well characterized. The role... The tricarboxylic acid(TCA) cycle is one of the canonical energy pathways of living systems, as well as being an example of a pathway in which dynamic enzyme assemblies, or metabolons, are well characterized. The role of the enzymes have been the subject of saturated transgenesis approaches, whereby the expression of the constituent enzymes were reduced or knocked out in order to ascertain their in vivo function.Some of the resultant plants exhibited improved photosynthesis and plant growth, under controlled greenhouse conditions. In addition, overexpression of the endogenous genes, or heterologous forms of a number of the enzymes, has been carried out in tomato fruit and the roots of a range of species, and in some instances improvement in fruit yield and postharvest properties and plant performance, under nutrient limitation, have been reported, respectively. Given a number of variants, in nature, we discuss possible synthetic approaches involving introducing these variants, or at least a subset of them, into plants. We additionally discuss the likely consequences of introducing synthetic metabolons, wherein certain pairs of reactions are artificially permanently assembled into plants, and speculate as to future strategies to further improve plant productivity by manipulation of the core metabolic pathway. 展开更多
关键词 On the role of the tricarboxylic acid cycle in plant productivity TCA cycle
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Global warming potential associated with Irish milk powder production 被引量:1
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作者 William Finnegan Jamie Goggins +1 位作者 Aksana Chyzheuskaya Xinmin Zhan 《Frontiers of Environmental Science & Engineering》 SCIE EI CAS CSCD 2017年第3期123-130,共8页
Climate change is an ever growing issue and a major concem worldwide. Both producers and processors need to address the issue now by reducing, their carbon footprint. Additionally, if Ireland is to meet their climate ... Climate change is an ever growing issue and a major concem worldwide. Both producers and processors need to address the issue now by reducing, their carbon footprint. Additionally, if Ireland is to meet their climate and energy targets, as outlined in Food Harvest 2020, which outlines a range ot objectives for the Irish agricultural sector, the efficient use of resources and fuels within the industry will need to be increased. In Ireland, agriculture accounts for 29.2% of the total greenhouse gas powder, is examined in order to estimate the global warming potential (GWP) associated with its manufacture using life cycle assessment. A cradle-to-processing factory gate analysis, which includes raw milk production, raw milk transportation to the processmg tactory, its processing into eacla product and product packaging, is assessed in this study using data collected circa 2013. The factories surveyed processed approximately 24% of the total raw milk processed in the Republic of Ireland in 2013, which was 5.83 billion liter. The average total GWP associated with the manufacture of milk powder is 9.731 kg CO2eq·kg^-1 milk powder, which has a standard deviation of 2.26 kg CO2eq·kg^-1 milk powder, for the life cycle stages analyzed in this study. The most significant contributor to GWP is raw milk production (84%), followed by dairy processing (14%), with the remainder of the life cycle stages contributing approximately 2%. 展开更多
关键词 Dairy Global wanning potential Ireland Life cycle assessment Milk powder Milk production
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Unimodality of Independence Polynomials of the Cycle Cover Product of Graphs
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作者 Bao Xuan ZHU 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2022年第5期858-868,共11页
An independent set in a graph G is a set of pairwise non-adjacent vertices.Let ik(G)denote the number of independent sets of cardinality k in G.Then its generating function I(G;x)=∑^(α(G))^(k=0)ik(G)x^(k),is called ... An independent set in a graph G is a set of pairwise non-adjacent vertices.Let ik(G)denote the number of independent sets of cardinality k in G.Then its generating function I(G;x)=∑^(α(G))^(k=0)ik(G)x^(k),is called the independence polynomial of G(Gutman and Harary,1983).In this paper,we introduce a new graph operation called the cycle cover product and formulate its independence polynomial.We also give a criterion for formulating the independence polynomial of a graph.Based on the exact formulas,we prove some results on symmetry,unimodality,reality of zeros of independence polynomials of some graphs.As applications,we give some new constructions for graphs having symmetric and unimodal independence polynomials. 展开更多
关键词 Independence polynomials UNIMODALITY LOG-CONCAVITY real zeros SYMMETRY cycle cover product of graphs
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Some Problems of Recycling Industrial Materials 被引量:2
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作者 CAI Jiu-ju LU Zhong-wu YUE Qiang 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2008年第5期37-41,55,共6页
The industrial system should learn from the natural ecosystem. The resource utilization efficiency should be increased and the environmental load should be decreased, depending on the materials recycled in the system.... The industrial system should learn from the natural ecosystem. The resource utilization efficiency should be increased and the environmental load should be decreased, depending on the materials recycled in the system. The classification of industrial materials from the viewpoint of large-scale recycling was stated. Recycling of materials, on three different levels, was introduced in the industrial system. The metal flow diagram in the life cycle of products, in the case of no materials recycled, materials partially recycled, and materials completely recycled, was given. The natural resource conservation and the waste emission reduction were analyzed under the condition of materials completely recycled. The expressions for the relation between resource efficiency and material recycling rate, and the relation between eco-efficiency and material recycling rate were derived, and the curves describing the relationship between them were protracted. The diagram of iron flow in the life cycle of iron and steel products in China, in 2001, was given, and the iron resource efficiency, material recycling rate, and iron eco-efficiency were analyzed. The variation of iron resource efficiency with the material recycling rate was analyzed for two different production ratios. 展开更多
关键词 RECYCLING industrial material product life cycle resource efficiency ECO-EFFICIENCY material recycling rate
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