变频软启动在44MW同步电动机上的应用

本文主要介绍变频软启动技术在邯钢公司44MW高炉鼓风机同步电动机上的应用。     

内置旁路型软起动器的替代性

本文根据软起动器的发展趋势，就目前市场上应用的三种类型的软起动器进行分析，说明各自的优缺点，同时给出结论，内置旁路型淘汰其它类型的软起动器的必要性。     

Application of selftuning regulator algorithm to generating unit controllers

The processing capability of computers makes it feasible to implement sophisticated techniques for process control. However, to minimize the software development costs, it is desirable to develop algorithms that can have a wider application. In keeping with this, an AVR and speed governor for a generating unit have been designed using the same algorithm, called the selftuning regulator. The selftuning AVR and speed governor have been implemented using a microprocessor and a minicomputer online. The feasibility of developing unified algorithms is demonstrated by means of realtime tests, in which the two controllers are used simultaneously for a generating unit physical model.     

Multiobjective optimisation of integrated energy systems for remote communities considering economics and CO2 emissions

The methods for designing, planning and managing integrated energy systems, while holistically considering the major economic and environmental factors, are still embryonic. However, the first phase of the design is often crucial if we want to manage resources better and reduce energy consumption and pollution. Considering integrated energy systems implies dealing with complex systems in which the synergy between the various components is best exploited (for example the thermal energy of a diesel engine produced during the night is complimented by the Rankine organic cycle of a solar thermal plant). The context of isolated communities further increases the difficulties when considering the long distance of transport required to supply fossil fuels. These sites are often located in very precarious environments, with limited or nonexistent resources except for solar energy, and with frequent additional needs for desalination (in arid zones).This paper illustrates a holistic method to rationalize the design of energy integrated systems. It is based on a superstructure (collection of models of all envisaged technologies) and a multi-objective optimisation (resources, demand, energy, emission, costs) using an evolutionary algorithm. The approach proposed allows the identification of more complete and more coherent integrated configurations characterizing the most promising designs (also taking into account the time dependency aspects). It also allows to better structure the information in view of a participative decision approach. The study shows that the economic implementation of renewable energy (solar) is even more difficult, compared to diesel based solutions, in cases of isolated communities with high load variations. New infrastructure or retrofit cases are considered.     

Power generation characteristics of a sandwich‐type self‐heating thermoelectric generator with spatially varying embedded heat source

Power generation characteristics of a sandwich‐type thermoelectric generator in which the heat source is embedded into thermoelectric elements are investigated. Our previous work on a similar concept only considered a uniform heat source distribution inside thermoelectric elements. In this work, the effect of the spatial distribution of a heat source is examined. In particular, the effect of the concentration of heat source near the one end, that is, the hot end, is intensively studied as a potential means of improving the efficiency of the device. Although the effects of heat source concentration in impractical cases without heat transfer limitations on the cold side remain ambiguous, it become clear that heat source concentration indeed has positive effects in more realistic cases with finite heat transfer coefficients imposed on the cold side. Because of the relatively low efficiency of typical thermoelectric generation, a significant amount of heat must be dissipated from the cold end of the thermoelectric element. Greater heat source concentration near the hot end leads to more effective utilization of available heat source, reduces the amount of heat rejected at the cold end, and lowers the hot end temperature of the thermoelectric element. Overall, it is suggested that heat source concentration can be used as a method to achieve more efficient operation and better structural integrity of the system. Copyright © 2015 John Wiley & Sons, Ltd.     

Transient analysis of a PV power generator charging a capacitor for measurement of the I–V characteristics

Measuring the I–V characteristics is of high importance since it can be considered as a quality and performance certificate for each PV generator. The most precise and inexpensive measuring method is represented in capacitor charging by the PV generator. Using the equivalent circuit of the PV generator with a capacitor as load and applying transient analysis on the circuit, we obtain the capacitor charging voltage and current as a function of time, as well as their differentials as a function of short circuit current and capacitor size. The derived equations facilitate the calculation of proper capacitance size for measuring the I–V characteristics, and considers the acquisition speed of the measuring system as demonstrated through two measurement samples in this paper. The capacitor size is directly and indirectly proportional to the short circuit current and open circuit voltage of the PV generator, respectively. Accordingly, the paper presents a capacitance calculation chart, which enables selecting the correct capacitance for measuring the I–V characteristics by a computerized data acquisition system.     

乳酸菌发酵剂对杂粮面团及馒头品质的影响

为研究混合乳酸菌发酵对杂粮面团及馒头品质的影响,将黄豌豆粉、莜麦粉、谷朊粉及燕麦β-葡聚糖（oatmeal β-glucan,OBG）复配成杂粮粉基质,利用直投式混合乳酸菌发酵剂发酵面团制作馒头。探究乳酸菌在面团中的酸化能力,分析杂粮面团中OBG、抗性淀粉（resistant starch,RS）和游离氨基酸含量的变化以及面团的微观结构变化,并对发酵前后的杂粮馒头和小麦粉馒头进行品质及营养特性比较。结果表明,在发酵杂粮面团中乳酸菌酸化能力强,发酵24 h后乳酸和乙酸质量浓度分别达到24.85、8.98 mg/mL。与未发酵的杂粮面团相比,乳酸菌发酵杂粮面团中OBG含量下降32.56%,RS含量上升32.88%,游离氨基酸总量提升至1.46倍,氨基酸组成模式更优,部分蛋白质和纤维素发生降解,面筋网络结构更加紧密且连续。在营养方面,乳酸菌发酵前后的杂粮馒头膳食纤维质量分数均高于6%,蛋白质质量分数分别为40.35%和38.38%,属于高纤维高蛋白食品,显著优于小麦粉馒头。乳酸菌发酵杂粮馒头具有更高的体外蛋白消化率和比容,且乳酸菌发酵杂粮馒头感官评价总评分显著高于未发酵杂粮馒头,整体可接受度...     

肉用乳酸菌发酵剂菌株的分离筛选与鉴定

作者从4种自然发酵肉制品中分离出112株乳酸菌,通过考察菌株的发酵特性和耐受性,最终获得一株性能优良的菌株T1-1。该菌株在添加8 g/dL NaCl和150 mg/kgNaNO2的MRS培养基中生长良好,并且能耐受80℃水浴10 min。通过生理生化鉴定和16S rRNA序列分析,该菌株为植物乳杆菌。     

不同发酵剂对北方风干香肠色泽和风味品质的改良作用

以不接菌的自然发酵样品为对照,分析商业发酵剂对北方风干香肠色泽和风味的改良作用。结合产品特点选取3 种不产酸,且具有护色增香功效的发酵剂。在生产过程中测定其色泽变化,并对最终产品进行感官评价、气相色谱-质谱（gas chromatography-mass spectrometry,GC-MS）联用分析和电子鼻分析。结果表明,3 种发酵剂的加入均能促进风干香肠产品色泽形成,即红度值a*显著增加。电子鼻传感器能够将4 组产品区分开,说明加入发酵剂后,风干香肠的风味有所改变。GC-MS结果显示,添加S-SX发酵剂和T-SC-200发酵剂能够显著增加产品风味物质含量,尤其是醛类、酮类、酯类风味物质相对含量有所提高。感官分析表明,S-SX发酵剂处理组的综合评分最高,其产品风味和口感更好。     

基于宏基因组分析四川泡菜母水作引子的泡菜发酵过程中细菌多样性变化

本文旨在研究以泡菜母水作引子的蔬菜发酵过程中细菌多样性变化,并对泡菜质量控制和泡菜中功能性细菌资源开发提供理论支持。采集发酵过程中不同发酵时间的样品,提取基因组,PCR扩增16S r RNA的V3+V4区并进行Illumina高通量测序,通过生物信息学分析比较发酵不同时间细菌多样性。结果表明:以老坛水作引子的发酵过程中发酵启动时魏斯氏菌属可达到74.5%,而之后则在10%左右,取而代之成为优势菌的是乳杆菌属,含量达到80%⁸5%。说明泡菜发酵中启动菌为魏斯氏菌属,发酵的关键菌为乳杆菌属,同时表明四川泡菜是优良的微生物资源,可用于魏斯氏菌属,乳杆菌属,乳球菌属,片球菌属和明串珠菌属等益生菌的分离和筛选。