电力市场环境下发电公司风险管理框架

在电力市场环境下,一方面,市场价格波动剧烈,发电公司在追求利润最大化的同时必须考虑相应的交易风险;另一方面,市场为发电公司提供了多种交易途径,以便其进行风险管理.因此,充分利用多种交易途径,为发电公司建立一个合适的风险管理框架是必需的,也是可能的.借鉴金融界广泛采用的风险管理方法,针对现有电力市场中各种交易途径及相应的风险,提出了一个用于发电公司电力交易的分层的风险管理框架.该框架包括目标及条件确认、风险控制和风险评估3个方面.其中,风险控制应用了风险规避及现代投资组合理论,风险评估采用VaR(value at risk)方法.该风险管理框架有助于发电公司明确交易目标,并制定计及风险因素的电能交易计划,从而在最大限度上降低整体交易风险,或者在发电公司可以承受的风险范围内使其利润最大化,即达到风险管理的目的--利润最大化和风险最小化.     

Rapid Assessment of Frying Performance Using Small Size Samples of Oils/Fats

A rapid, effective test mimicking actual frying was developed to assess the frying performance of oils and fats using small size samples. To a small volume of the oil to be tested, a formulated food consisting of gelatinized potato starch, glucose and silica gel (4:1:1 w/w) were added and content heated at 185 ± 5 °C with mixing for 2 h. Thermo-oxidative degradation of the oil was assessed by the measurement of the total amount of polar components and their composition, including degradation of tocopherols. The developed fast test accurately mimics actual frying done using an institutional fryer as assessed by the accumulation and composition of total polar components and the amount of residual tocopherols. The validity of the test was assessed using the following oils: regular canola, high oleic– low linolenic canola, and high oleic sunflower. Comparison of data between the fast frying test and institutional frying revealed a lack of significant differences. The developed frying test provides reliable quantitative and qualitative data describing the performance of the frying oil/fat. The rapid frying procedure allows assessment of the frying performance of oils at the early stages of development where usually only small amounts of the sample are available and when a large number of samples have to be tested assessing effects of oil additives.     

Doublecortin May Play a Role in Defining Chondrocyte Phenotype

Embryonic development of articular cartilage has not been well understood and the role of doublecortin (DCX) in determination of chondrocyte phenotype is unknown. Here, we use a DCX promoter-driven eGFP reporter mouse model to study the dynamic gene expression profiles in mouse embryonic handplates at E12.5 to E13.5 when the condensed mesenchymal cells differentiate into either endochondral chondrocytes or joint interzone cells. Illumina microarray analysis identified a variety of genes that were expressed differentially in the different regions of mouse handplate. The unique expression patterns of many genes were revealed. Cytl1 and 3110032G18RIK were highly expressed in the proximal region of E12.5 handplate and the carpal region of E13.5 handplate, whereas Olfr538, Kctd15, and Cited1 were highly expressed in the distal region of E12.5 and the metacarpal region of E13.5 handplates. There was an increasing gradient of Hrc expression in the proximal to distal direction in E13.5 handplate. Furthermore, when human DCX protein was expressed in human adipose stem cells, collagen II was decreased while aggrecan, matrilin 2, and GDF5 were increased during the 14-day pellet culture. These findings suggest that DCX may play a role in defining chondrocyte phenotype.     

Antivitamins for Medicinal Applications

Antivitamins represent a broad class of compounds that counteract the essential effects of vitamins. The symptoms triggered by such antinutritional factors resemble those of vitamin deficiencies, but can be successfully reversed by treating patients with the intact vitamin. Despite being undesirable for healthy organisms, the toxicities of these compounds present considerable interest for biological and medicinal purposes. Indeed, antivitamins played fundamental roles in the development of pioneering antibiotic and antiproliferative drugs, such as prontosil and aminopterin. Their development and optimisation were made possible by the study, throughout the 20th century, of the vitamins' and antivitamins' functions in metabolic processes. However, even with this thorough knowledge, commercialised antivitamin‐based drugs are still nowadays limited to antagonists of vitamins B₉ and K. The antivitamin field thus still needs to be explored more intensely, in view of the outstanding therapeutic success exhibited by several antivitamin‐based medicines. Here we summarise historical achievements and discuss critically recent developments, opportunities and potential limitations of the antivitamin approach, with a special focus on antivitamins K, B₉ and B₁₂.     

First X-ray structure of discrete anion [HgBr5]: Synthesis, characterization and single crystal X-ray structure determination of [Co(NH3)6][HgBr5]

A new cobalt(III) complex salt, [Co(NH₃)₆][HgBr₅](1) was crystallized from a solution of hexaamminecobalt(III)bromide and potassium tetrabromomercurate(II) in aqueous medium in 1:1 molar ratio. This complex salt has been characterized by elemental analyses, spectroscopic techniques (e.g. UV/Visible, IR), solubility product and conductance measurements. The complex salt crystallizes in Orthorhombic crystal system with space group Pnma. Single crystal X-ray structure determination revealed the presence of discrete ions: [Co(NH₃)₆]³⁺ cation and a new anion [HgBr₅]³⁻. This is the first structural report of a complex salt containing this new anion. The structure consists of stacks of cations and anions demonstrating supramolecular arrangements through N–HBr hydrogen-bond interactions. The crystal lattice is stabilized by these non-covalent interactions besides electrostatic interaction.     

Thermal analysis and optimization of a portable,edge-air-cooled PEFC stack

Internally humidified, edge-air-cooled PEFC stacks are promising for portable systems in terms of specific power and specific cost. However, their main drawbacks are thermal power limitations due to limited heat removal from inside the stack. The aim of this work is to minimize the cooling limitation with a simultaneous cost and weight reduction by optimization of the stack geometry. A steady-state, thermal FE-model was developed and validated against experimental temperature distributions. The model includes anisotropic heat conduction and heat convection by the cooling air. Cell voltage, liquid water fraction and limiting temperature were experimentally determined for improved accuracy. Complex flowfield structures were approximated with the numerical volume averaging method to reduce computational cost. As a result of the optimization study specific power was improved by +86% with simultaneous reduction of specific cost by −35$-35$%.     

SAS-TDMA: a source aware scheduling algorithm for real-time communication in industrial wireless sensor networks

Scheduling algorithms play an important role for TDMA-based wireless sensor networks. Existing TDMA scheduling algorithms address a multitude of objectives. However, their adaptation to the dynamics of a realistic wireless sensor network has not been investigated in a satisfactory manner. This is a key issue considering the challenges within industrial applications for wireless sensor networks, given the time-constraints and harsh environments. In response to those challenges, we present SAS-TDMA, a source-aware scheduling algorithm. It is a cross-layer solution which adapts itself to network dynamics. It realizes a trade-off between scheduling length and its configurational overhead incurred by rapid responses to routes changes. We implemented a TDMA stack instead of the default CSMA stack and introduced a cross-layer for scheduling in TOSSIM, the TinyOS simulator. Numerical results show that SAS-TDMA improves the quality of service for the entire network. It achieves significant improvements for realistic dynamic wireless sensor networks when compared to existing scheduling algorithms with the aim to minimize latency for real-time communication.