Tilt Angle Optimality Criteria for Stand Alone PV Systems

The conventional approach to optimizing tilt angles for fixed solar panels aims to maximize energy generation over the entire year. However, in the context of a supply controlled electric grid, where solar energy availability varies, this criterion may not be optimal. This study explores two alternative optimization criteria focused on maximizing baseload supply potential and minimizing required storage capacity to address seasonality in energy generation. The optimal tilt angles determined for these criteria differed significantly from the standard approach. This research highlights additional factors crucial for designing solar power systems beyond gross energy generation, essential for the global transition towards a fully renewable energy-based electric grid in the future.

Coupling trade-offs and supply-demand of ecosystem services(ES):A new opportunity for ES management

The trade-offs and supply-demand relations of ecosystem services(ES)are at the frontier of geographical and ecological studies.However,previous studies have focused on either trade-offs or the supply-demand aspects,while ES conflicts and supply/demand contradictions have not been comprehensively examined.The relation-ship between ES trade-offs and supply-demand is logically valid and studying the coupling of both can provide approaches for simultaneously alleviating ES conflicts and supply-demand contradictions.This study,based on a review of previous analyses of ES trade-offs and supply-demand dynamics,proposes a new analytic framework to couple them.First,we define two types of trade-offs based on the directions of growth or decline of the two ser-vices.We also define the supply-demand balance area and the supply-demand risk area according to the ES flow characteristics.Second,the mechanisms driving ES trade-offs are clarified,and land-use scenarios are set based on the mechanisms.Third,the supply-demand spatial characteristics of ES are analyzed,and supply-demand risk areas are identified.Finally,scenario iterations are performed to minimize the supply-demand risk area at an acceptable trade-offintensity to identify an optimal land use plan,which simultaneously alleviates ES conflicts and supply-demand contradictions.This analytic framework offers new opportunities for improving sustainable ecosystem management.

The Supply-Demand Analysis and Mechanism Innovation of Chinese Rural Public Goods

The connotation of rural public goods is expounded.The rural public goods refer to the products and labors that satisfy the production and living of rural residents,economic growth and social progress.The rural public goods is characterized by non-excludability,non-competitiveness and indispensability of other general public goods.The supply situation of Chinese government to rural public goods is analyzed,as well as the demand situation of rural public goods,which includes farmers' demand on training,the assistance demand of rural weak groups,farmers' demand on comfortable living conditions and farmers' demand on "soft" public goods.The paths for innovating the supply mechanism of rural public goods are put forward,which cover perfecting the decision mechanism of public goods supply;scientifically distributing the supply responsibility of rural public goods;facilitating the reform of each supporting equipment and exploring the multiple capital collecting channels of rural public goods.

A comparison of coal supply-demand in China and in the US based on a network model

Through analysis the actual coal supply and demand in the US and China, the properties of the coal supply-demand market in both countries are investigated based on the energy supply-demand network. The validity of our model is verified by comparing numerical results with empirical results. The comparison of empirical results and the comparison of coal network model parameters between in the US and in China reveal the essence of the internal differences and similarities of coal supply and demand in these two countries. The third stage of China＇s coal network was close to that of the US in 1995, indicating that the evolutional situation of China＇s coal market begins to transit to an oligopolistic type. Finally, suggestions for China＇s coal supply-demand strategy are put forward.

China＇s Graphite Resources and the Supply-Demand Situation

Graphite is a rare and important nonmetallic mineral. Till 2017, the global graphite resource reserves had exceeded one billion tons, which are mainly distributed in China （0.45 billion tons）, Mozambique （0.14 billion tons）, Madagascar （0.1 billion tons）, Turkey （0.09 billion tons）, Brazil （0.07 billion tons）, and Tanzania （0.07 billion tons）. These six countries include about 92% of the global graphite resource reserves, of which China accounts for about 45% of the world＇s total resource reserves.

Supply-Demand Situation and Exploration of Mineral Resources in China during 2016-2017

During 2016-2017,both the supply and demand of China’s main mineral resources continued to grow.The import of major energy resources and metal ore resources,such as iron ores,crude oil,natural gas,coal and bauxite,except for copper,has shown a substantial increase(Table1).In order to guarantee economic development needs,the

Farmer's Perception on Supply-Demand Matching of New Variety and Its Influence Factors

Using disordered multinomial logistic regression and multiple linear regression method,385 copies of questionnaires on farmer are analyzed to explore the relationship between peasant's psychological traits,peasant's cognition on seed technology and perception on supplydemand matching of new variety.Research results show that the vast majority of farmers think that current new variety is at high-level supplydemand balance and the oversupply status,and updating speed of new variety on the market is faster;the farmers preferring risk,seeking innovation and having strong learning and cognition ability may select high-level supply-demand matching state,and the farmers understanding the importance and difference of seed technology tend to choose high-level supply-demand matching situation;the farmers with strong learning and cognition ability can acknowledge the importance and difference of seed technology,while the farmers preferring risk can perceive the difference of seed technology;psychology seeking the innovation and learning and cognition ability affect the farmer's perception on supplydemand matching status of new variety via affecting the farmer's cognition on technical difference.

Optimization Model for School Transportation Based on Supply-Demand Analyses

This paper presents a new conception model of school transportation supply-demand ratio (STSDR) in order to define the number of school buses needed in a limited area and to describe the conditions of school transport system. For this purpose, a mathematical equation was elaborated to simulate the real system based on the school transport conditions and on the estimated results of STSDR from 15 zones of Cuenca city in Ecuador. The data used in our model was collected from several diverse sources (i.e. administrative data and survey data). The estimated results have shown that our equation has described efficiently the school transport system by reaching an accuracy of 96%. Therefore, our model is suitable for statistical estimation given adequate data and will be useful in school transport planning policy. Given that, it is a support model for making decisions which seek efficiency in supply and demand balance.

Study upon the Spatial Structure of Regional Eco-tourism-Based upon the Perspective of Supply and Demand and Competition Field

Along with the coming of the low-carbon era, people have paid more and more attention to the natural environment and eco-tourism will embrace a huge development. From the perspectives of the market relationship of supply-demand in economics and of field competition in physics, this paper has discussed upon the present status of the spatial structure of eco-tourism, and analyzed the relationship between supply-demand and field, in order to clarify the direction for the balance between supply and demand in the field and to guide eco-tourism to the way of sustainable development.

上海市全科医生供需整合预测模型构建及响应策略模拟

目的构建上海全科医生供需整合的预测模型,进行政策的情景模拟,为解决上海全科医生供需失衡问题提供建议与策略。方法基于供给和需求的预测结果,计算上海全科医生的供需缺口,对增加供给和合理引导需求后全科医生的供需情况进行情景分析。结果根据供需整合预测结果,扩大全科规范化培训招生规模后,当需求参数保持不变时,2030年上海全科医生供需差值将达到578人,每万常住人口的全科医生供需差值将达到0.2人;扩大全科规范化培训招生规模后,当需求参数基于既往趋势变化时,2030年上海全科医生供需差值将达到2929人,每万常住人口的全科医生供需差值为1.1人。上海全科医生供需面临的风险主要为供不应求,通过增加全科医生的培养数量与扩大区域外招聘规模,可以缓解部分供需缺口;高龄化、首诊在社区等人口与政策的变化会增加全科医生的需求,从而扩大供需缺口。结论基于供需整合视角进行全科医生数量预测能够为更加系统、前瞻性地解决供需失衡问题提供综合、有力的证据支持。供需整合的系统动力学模型可以为模拟响应策略提供技术支持,其预测结果可以为上海全科医生的规划提供决策参考。

Oil and Gas Supply and Demand in China and Its Development Strategy

The paper makes a comprehensive prediction of China＇s future demand for oil and gas with two methods, i.e. the prediction method based on the demand for individual oil and gas products and the method for predicting the total demand. According to the demand prediction of, and the historical data on, the oil and gas consumption, we conduct an analysis of the oil and gas consumption trends, which can be described as six different development periods. On the other hand, the paper makes a comprehensive analysis of the domestic oil and gas resources and, on this basis, makes a basic prediction of the domestic output of oil and gas. The supply and demand situation is also analyzed. By using the SWOT analysis method, the paper puts forward the development strategies for China＇s oil and gas industry and gives some related strategic measures.

Multi-scale coupling analysis of urbanization and ecosystem services supply-demand budget in the Beijing-Tianjin-Hebei region, China

Rapid economic development and human activities have severely affected ecosystem function.Analysis of the spatial distribution of areas of rapid urbanization is the basis for optimizing urban-ecological spatial design.This paper evaluated the spatial distribution of urbanization in the Beijing-Tianjin-Hebei(BTH)region,and then quantified the ecosystem services(ES)budget in the region based on an ES supply and demand matrix.The results showed that(1)urbanization patterns in the BTH region were relatively stable from 2000 to 2015,with clear patterns of low levels of urbanization in the northwest and high levels in the southeast;(2)areas with positive ES budget values were found throughout the region,except in built-up areas,with high ES supply areas concentrated in the northwest,and high ES demand areas in the southeast;(3)at both the county and prefecture-city levels,urbanization had negative,positive,and negative correlations with ES supply,demand,and budget,respectively;(4)the coupling coordination degree(CCD)increased,with high CCD values in the southeast.Based on these results,policy recommendations include strengthening rational land-use planning and ecosystem management,promoting the coordinated development of the economy and ecological function,and coordinating the provision of production-life-ecological functions.

Analysis and Forecast of China’s Grain Supply and Demand Quality Grade Structural Balance

Based on the analysis of China’s grain production and demand quality grade, this paper uses the non-equidistance GM (1,1) model and the inference algorithm to predict the structural balance of the supply and demand grades of China’s four major grain crops. The results show that the supply and demand for wheat, corn and rice can maintain a quantitative balance. While, it’s difficult to achieve a quality grade balance in wheat and rice and keep a supply and demand balance in terms of quantity and quality of soybean. Simultaneously, the supply of premium grade corn is greater than the demand. The analysis and prediction results can reflect the existing structural balance matter of grain supply and demand at different quality grades in China, and provide theoretical basis for governments to formulate relevant policies.

Estimation Methodology of Short-term Natural Rubber Price Forecasting Models

This study developed a short-term econometric model of world natural rubber price Standard Malaysia Rubber Grade 20 （SMR20）. Both single and simultaneous equations were utilized using monthly data from January 1990-December 2008 as estimation period and data from January 2009-June 2009 was used as an ex-ante forecast. The data were tested for unit root and Vector Error Correction and co-integration method was used to estimate the parameters of the model. The models specifications were developed in order to discover the inter-relationships between NR production, consumption and prices of SMR20 and to determine forecast price of SMR20. Comparative analysis between the single-equation specification and simultaneous supply-demand and price equation were made in terms of their estimation accuracy based on RMSE, MAE and （U-Thile） criteria. Ex-ante forecasts was carried out for the period of January 2009-June 2009. The results revealed that the values of the RMSE, MAE and U of simultaneous supply-demand and price equations model were comparatively smaller than the values generated by the single-equation model. These statistics suggest that the simultaneous equation of supply-demand and price model is more accurate and efficient measure in terms of its statistical criteria than the single-equation model in predicting the price of SMR20 in the next 6 months.

界定土地利用面积值并优化其结构以改善生态系统服务供需平衡状态

Improving the supply-demand balance of ecosystem services(SDBES)from the perspective of land use is essential for managing regional ecosystem and realizing sustainable development.By combining land use with the supply and demand of ecosystem services(SDES),a technical framework for defining land use threshold and optimizing its structure to improve the SDBES state was constructed and applied to a practical case.The spatial pattern of supply and demand of each ES in Lancang county was distinctly heterogeneous,with significant differences in SDES across different land use types.Strong spatial heterogeneity existed in the ESDR of each ES at the grid scale,and the areas of deficit were ranked as carbon sequestration>water conservation>habitat quality>food production.The structure of dry land,paddy field,tea,evergreen broad-leaved forest,grassland,urban construction land,and industrial and mining construction land were the focus of land use optimization.Based on the land use area thresholds under the SDBES,the optimal land use structure for maximizing comprehensive benefits contributed to a balanced relationship between SDES and promoted sustainable regional development.The study provides a new perspective and method for improving the SDBES state,alleviating land conflicts,and managing ecological environment.

Spatial patterns of ecological carrying capacity supply-demand balance in China at county level

A balanced ecological carrying capacity and its understanding are important to achieve sustainable development for human kind.Here,the concept of ecological carrying capacity has been used for measuring the dependencies between human and nature.China＇s ecological balance between supply and demand has become a global concern and is widely debated.In this study the ＇Ecological Footprint＇ method was used to analyze the supply-demand balance of China＇s ecological carrying capacity.Firstly,the ecological supply and demand balance was calculated and evaluated,and secondly,the ecological carrying capacity index （ECCI） was derived for each county of China in 2007,and finally this paper systematically evaluated the ecological carrying capacity supply-demand balance of China.The results showed that ecological deficit appeared to be the main characteristic of ecological carrying capacity supply-demand balance in 2007 of China at county scale.In general,more than four-fifths of the Chinese population was concentrated in less than one-third of the land area and more than two-thirds of the land area was inhabited by less than one-fifth of the population.The spatial distribution of the ecological carrying capacity demand-supply was unbalanced ranging from significant overloading to affluence from southeastern to northwestern part of China.It appeared to be more dominant in regions located at coastal areas which are attracted by migrants and had a generally higher population density.Along with the rapid development and urbanization trends in China,ecological deficits in these regions will become more severe.

Plant-Wide Supply-Demand Forecast and Optimization of Byproduct Gas System in Steel Plant

Considerable energy is consumed during steel manufacturing process. Byproduct gas emerges as secondary energy in the process; however, it is also an atmospheric pollution source if it is released into the air. Therefore, the optimal utilization of byproduct gas not only saves energy but also protects environment. To solve this issue, a fore- cast model of gas supply, gas demand and surplus gas in a steel plant was proposed. With the progress of energy conservation, the amount of surplus gas was very large. In a steel plant, the surplus gas was usually sent to boilers to generate steam. However, each boiler had an individual efficiency. So the optimization of the utilization of surplus gas in boilers was a key topic. A dynamic programming method was used to develop an optimal utilization strategy for surplus gas. Finally, a case study providing a sound confirmation was given.

A Review on the Supply-Demand Relationship and Spatial Flows of Ecosystem Services

Research on spatial flow as it relates to the relationship between the supply and demand of ecosystem services supports a significant connection between the supply of ecosystem services and human well-being.Understanding the entire process of the production and flow,as well as the use of ecosystem services,accurately assessing the balance of supply and demand of ecosystem services,and establishing a two-way feedback relationship between supply and demand are vital for the scientific management of the ecosystem and ensuring the sustainable development of regional resources.Based on a large number of relevant publications,this paper comprehensively summarizes the concepts and assessment methods of ecosystem service supply and demand from the perspective of ecosystem service supply and demand,and discusses the impacts of land use and climate change on the temporal and spatial changes of ecosystem services under the background of global change.Then,an analysis of the research progress in the ecosystem services spatial flow indicated that there are still deficiencies in the quantification of cultural services,the dynamics of ecosystem service flow and the driving mechanism of ecosystem services.We also propose that clarifying the driving mechanism and transfer process of ecosystem services,and realizing the mutual conversion between different spatial-temporal scales of ecosystem services,is an important approach for improving the application of ecosystem services research in practice in the future.

Supply-Demand Analysis of Urban Emergency Shelters Based on Spatiotemporal Population Estimation

Supply–demand analysis is an important part of the planning of urban emergency shelters.Using Pudong New Area,Shanghai,China as an example,this study estimated daytime and nighttime population of the study area based on fine-scale land use data,census data,statistical yearbook information,and Tencent user-density big data.An exponential function-based,probability density estimation method was used to analyze the spatial supply of and demand for shelters under an earthquake scenario.The results show that even if all potential available shelters are considered,they still cannot satisfy the demand of the existing population for evacuation and sheltering,especially in the northern region of Pudong,under both the daytime and the nighttime scenarios.The proposed method can reveal the spatiotemporal imbalance between shelter supply and demand.We also conducted a preliminary location selection analysis of shelters based on the supply–demand analysis results.The location selection results demonstrate the advantage of the proposed method.It can be applied to identify the areas where the supply of shelters is seriously inadequate,and provide effective decision support for the planning of urban emergency shelters.

Unpacking the‘supply-utilization-demand’interplay:Keys to multifunctional sustainability in rural China

Sustainable rural development is predicated on a delicate balance between rural territorial functions and eco-logical constraints.While various functions can catalyze economic growth in rural settings,aligning them with inherent ecological variables is essential.An exhaustive analysis of Beijing’s Pinggu District elucidated specific supply-demand thresholds and evaluated the adaptability of current utilization within these boundaries,culmi-nating in a novel optimization strategy.Notably,while locals place significant emphasis on production functions,the area’s topography and soil characteristics present palpable challenges to achieving these goals.We discov-ered that‘shackle type’predominantly characterize individual rural territorial functions,while‘diversified weak function optimization type’define multifunctional aspects,showcasing varied development paths and uncov-ering potential strategies for sustainable improvement.This study contributes a groundbreaking perspective to sustainable rural development,offering key insights and strategic recommendations for policy formulation.