Optimal investment paths for future renewable based energy systems—Using the optimisation model Balmorel

This paper investigates a possible long term investment path for the Nordic energy system focussing on renewable energy in the supply sector and on hydrogen as the main fuel for transportation, covering up to 70% of all transport in 2050.     

Sustainable energy system – A case study from Chile

This paper presents some of the results of a power system analysis for Chile. The two major Chilean electric systems are roughly modelled and optimized using a linear programming method with the option to integrate renewable energy sources like wind power, solar power, mini-hydropower and biomass-fired power and also “municipal waste”. A total of four different scenarios are outlined: reference system, new production units, gas and coal price variations and a policy measure to encourage power production based on renewable energy. The objective of the scenarios was to illustrate under what conditions integration of the different energy sources in the existing production system is possible. The study shows that even under current conditions, mini-hydro and waste to energy plants are economically viable. Wind power might be interesting alternatives if policy instrument measures are applied. On the other hand, it is hard for the other energy sources to enter the system even when higher price levels of gas and coal are applied. The system is more sensitive to coal price increases than to gas price increases and this mainly encourages CO₂ emission reduction.     

The muse approach to Or-parallel prolog

Muse (Multi-sequential Prolog engines) is a simple and efficient approach to Or-parallel execution of Prolog programs. It is based on having several sequential Prolog engines, each with its local address space, and some shared memory space. It is currently implemented on a 7-processors machine with local/shared memory constructed at SICS, a 16-processors Sequent Symmetry, a 96-processors BBN Butterfly I, and a 45-processors BBN Butterfly II. The sequential SICStus Prolog system has been adapted to Or-parallel implementation. Extra overhead associated with this adaptation is very low in comparison with the other approaches. The speed-up factor is very close to the number of processors in the system for a large class of problems.The goal of this paper is to present the Muse execution model, some of its implementation issues, a variant of Prolog suitable for multiprocessor implementations, and some experimental results obtained from two different multiprocessor systems.     

Preface

The reliability of GaAs microwave devices is directly related to the integrity of Schottky and ohmic contacts for Schottky barrier devices and metal/semiconductor field effect transistor devices. The interface analysis of these device structures using surface analysis techniques has become extremely important in the study of the degradation of these devices. The research reported here focuses on three different metallic systems, namely Au/In, Au-12 wt.% Ge and Ni/AuGe, for both Schottky and ohmic contacts. The three metallic systems were evaporated onto 〈100;〉- oriented GaAs substrates (N_D=3×10¹⁷cm^-3) in an ultrahigh vacuum system. These samples were thermally aged by keeping them at 150°C for 500h. Current-voltage and capacitance-voltage measurements were made on as-deposited and thermally aged samples. The ideality factor decreased in all the samples. There was an apparent large increase in barrier height in AuGe/GaAs and Ni/AuGe/GaAs Schottky diodes. There was an insignificant change in the contact resistivity of ohmic contacts after thermal aging.The changes in the electrical characteristics of these device structures are explained on the basis of the formation of an oxide layer after thermal aging. A comparison of the Auger depth profiles of the as-deposited and the thermally aged samples substantiates the electrical observations. However, Au/In/GaAs Schottky diodes do not show the existence of an oxide layer at the interface. The out-diffusion of indium to the surface might have removed the oxygen from the interface to result in an Au-GaAs interface in the thermally aged sample. A slight increase in the barrier height of this sample is due to the Au-GaAs interface rather than the In-GaAs interface.     

省级电力行政交换网软交换改造方案研究

目前省级电力行政交换网大多采用程控交换设备组网,随着程控交换设备的逐步停产和电力系统业务多样化的发展需求,急需进行行政交换网升级改造工作。文章分析了软交换与IMS的商用情况,提出了近期省级电力行政交换网改造的技术体制选择建议、改造原则、建设模式、互联互通方案和下级站点典型接入方案。旨在为近期各省／市行政交换网改造提供方案参考。     

Time trends of selected persistent organic pollutants in lake sediments from Greenland

Sediments from seven lakes in West Greenland were used as natural archives to study past and present levels of PCBs (polychlorinated biphenyls, tri- to decachlorinated), tetra-BDE #47 (2,2',4,4'-bromodiphenyl ether), chlordane (cis- and trans-octachlordane) and HxCBz (hexachlorobenzene). The concentrations found are lower than or comparable to concentrations found in sediments from other Arctic regions and one to 2 orders of magnitude lower than concentrations typically found in sediments at lower latitudes. The observed temporal trends (direct and indirect dating) show a decreasing total PCB concentration. Even though local contamination sources exist, the POP deposition in the studied area is most likely a result from long-range transport. The hypothesis about "cold condensation" suggests a latitudinal fractionation to occur between different volatile compounds during the transport toward the pole. In this study a time delay in the deposition for the low-chlorinated PCBs (tri- and tetrachlorinated), compared to their emission histories and compared to higher chlorinated PCBs, was indicated. Although very low tetra-BDE #47 concentrations are observed in this study, there are indications for an increasing concentration in recent sediment layers that may reflect increasing environmental concentrations at lower latitudes. The investigated pesticides are still in use at lower latitudes, however neither chlordane nor HxCBz show any distinct temporal trend of increasing or decreasing concentration toward the sediment surface.     

A study of a high-resolution linear circuit for capacitive sensors

A circuit for capacitance measurements is described. The circuit permits offset capacitance compensation using a dc voltage. The electronic circuitry with its testing is described. The output voltage is a linear function of the capacitance measured. Experimental data show good agreement with values predicted by the linear formula. Experiments show it is possible to measure capacitance changes with a resolution of a few femtofarads (fF)     

The Incompleteness Problem of the APT Model

The Arbitrage Pricing Theory provides a theory to quantify risk and the reward for taking it. While the theory itself is sound from most perspectives, its empirical version is connected with several shortcomings. One extremely delicate problem arises because the set of observable asset returns rarely has a history of complete observations. Traditionally, this problem has been solved by simply excluding assets without a complete set of observations from the analysis. Unfortunately, such a methodology may be shown to (i) lead for any fixed time period to selection bias in that only the largest companies will remain and (ii) lead to an asymptotically empty set containing no observations at all. This paper discusses some possible solutions to this problem and also provides a case study containing Swedish OMX data for demonstration.     

UPM芬欧汇川开发生物燃料转型趋向低碳经济

欧洲是全球提出低碳理念发展最早的地区,其在低碳经济的理论研究、取得成果以及研发投入等方面,也一直处于世界的前端.为迎接全球低碳时代的来临,欧盟按照欧盟委员会2007年确立的能源和碳减排目标:到2020年欧盟的温室气体排放应减少20%(如果条件合适将提高到30%),可再生能源比例达到20%,同时将能源利用效率提高20%,交通运输业生物燃料的使用达到10%.