含矩形边缘分层缺陷层合板的压缩性能

对含矩形边缘分层缺陷层合板的压缩性能进行试验研究和理论分析, 考察了层合板厚度(含铺层形式)、 分层位置、 形状、 面积以及环境等因素对压缩强度的影响, 并采用分层扩展以及软化夹杂两种模型对含分层层合板的压缩强度进行了计算和破坏机理分析。结果表明: 厚板对边缘分层缺陷不敏感, 中等厚度和薄层合板比较敏感; 缺陷的位置和形状对层合板压缩强度有一定的影响; 湿热环境改变了含缺陷板的压缩破坏机理, 并对中等厚度板和薄板的压缩强度有明显的影响。两种模型中软化夹杂模型效果较好, 可用于工程设计计算。      

HIGH-TEMPERATURE DRYING-CUM-PARBOILING OF PADDY

Alternate methods of parboiling of paddy, in place of conventional steam-parboiling, for obtaining improved hydration ability in the parboiled rice were explored. Ratnachudi variety, a medium-grained, tall indica, high-amylose rice, was used. The paddy was soaked in warm water to a saturation moisture level (ca 30%, w.b.). The soaked paddy was dried by either exposing it to very hot air (150°—200°C) or by roasting it in hot sand (250°—300°C) for a few minutes. It was observed that under appropriate high-temperature conditions paddy got simultaneously dried and parboiled by both the above treatments. Parboiled rice so produced was examined for appearance (translucence, color), milling breakage, alkali degradation pattern and starch retrogradation. It was found to be quite comparable to normal steam-parboiled rice in all respects, except that it showed the desirable property of improved hydration ability due to lowering of starch retrogradation. Possible development of the technique into commercial process is indicated.     

HYDROGEN SULFIDE PRODUCTION BY HEATING DIFFERENT PROTEIN FRACTIONS OF TUNA MEAT

Raw albacore tuna was separated into water-soluble and water-insoluble fractions. The water-soluble fraction was separated into two fractions by trichloroacetic acid (2.5%). The water-insoluble fraction was extracted with NaCl (0.45 M), and then the insoluble fraction was further extracted with urea solution (6 M). H₂S production upon heating of each fraction was determined by the reflux-trap technique. Water-soluble proteins produced 71% of the H₂S, while the corresponding contribution from the insoluble fraction was 29%. Non-protein soluble components and salt-soluble proteins produced insignificant amounts of H₂S. Significant increase in the amount of H₂S was observed when water-insoluble proteins were treated with urea and TCA solutions.     

Experimental Analysis of a Solar Energy Storage Heat Pump System

This paper introduces a novel solar-assisted heat pump system with phase change energy storage and describes the methodology used to analyze the performance of the proposed system. A mathematical model was established for the key parts of the system including solar evaporator, condenser, phase change energy storage tank, and compressor. In parallel to the modelling work, an experimental set-up of the proposed solar energy storage heat pump system was developed. The experimental data showed that the designed system is capable of meeting cold day heating demands in rural areas of Yanbian city located in Jilin province of China. In day-time operation, the solar heat pump system stores excess energy in the energy storage tank for heating purposes. A desired indoor temperature was achieved; the average coefficient of performance of solar heat pump was identified as 4.5, and the system showed a stable performance throughout the day. In night-time operation, the energy stored in the storage tank was released through a liquid-solid change of phase in the employed phase-change material. In this way, the provision of continuous heat for ten hours was ensured within the building, and the desired indoor air conditions were achieved.     

SUPERCRITICAL CARBON DIOXIDE TREATMENT TO INACTIVATE AEROBIC MICROORGANISMS ON ALFALFA SEEDS

The supercritical carbon dioxide (SC-CO₂) process involves pressurizing CO₂ in a chamber which generates liquid phase of carbon dioxide. Pressurized liquid CO₂ has a strong extraction capability of organic and inorganic compounds. The recent studies have also demonstrated that antimicrobial effect of SC-CO₂ due extraction some cellular components of microorganisms. The efficacy of a supercritical carbon dioxide treatment on alfalfa seeds contaminated with Escherichia coli K12 was tested at 2000, 3000, and 4000 psi at 50C. Samples were treated for 15, 30, and 60 min at each pressure. After pummeling the seed samples in 0.1% peptone water, the initial and final Escherichia coli and total aerobic bacteria on the seeds were determined by plating on 3M Petri Films. After 48 h of incubation at 37 C, the colonies were enumerated. Treated seeds were evaluated in terms of germination characteristics. For aerobic plate count, the effect of pressure in the range of 2000–4000 psi was not statistically significant (p > 0.05) even though 85.6% inactivation was achieved at 4000 psi for 60 min. For E. coli, the reductions for 2000, 3000, and 4000 psi treatments for 15 min were 26.6, 68.1, and 81.3%, respectively. As the time was increased from 15 to 60 min at 4000 psi, the percent E. coli reduction increased from 81.3% to 92.8%. The percent germination for all treatments was over 90%. There was no significant difference (p > 0.05) in the germination rate of treated and untreated seeds. Supercritical carbon dioxide treatments demonstrated a reduction of E. coli K12 and total aerobic counts without affecting the germination characteristics of alfalfa seeds (p < 0.05). This study was a step in the direction of improving safety of alfalfa seeds used to produce fresh sprouts, which have been the cause of several outbreaks.     

Effects of Mentha longifolia L. essential oil and Lactobacillus casei on the organoleptic properties and on the growth of Staphylococcus aureus and Listeria monocytogenes during manufacturing,ripening and storage of Iranian white‐brined cheese

This research evaluated the effects of Mentha longifolia L. essential oil (EO) in concentrations 0, 50, 150 and 300 ppm and Lactobacillus casei (10⁸–10⁹ CFU/mL) on the growth of Staphylococcus aureus and Listeria monocytogenes during the manufacturing, ripening and storage of Iranian white‐brined cheese. The growth of the two pathogens was significantly reduced (P < 0.01) by both EO concentrations ≥50 ppm and probiotic and their combination in the standard manufacturing and storage process conditions of the cheese. Furthermore, the treatment containing 150 ppm of this EO combined with probiotic had a favourable inhibitory effect on the growth of two pathogenic micro‐organisms and also was the most appropriate treatment in sensory assessment. The synergistic effects of the above‐mentioned concentration level between the essential oil and probiotic were significant compared to other treatments, including essential oil and probiotic only. Thus, a lower concentration of this EO can be used when it is combined with this probiotic.     

CHANGE OF FAT CONTENT AND FATTY ACID COMPOSITION OF TURKISH HAZELNUTS (CORYLUS AVELLANA L.) DURING STORAGE

Hazelnuts (Corylus avellana L.) were collected from three different cultivars (Tombul, Palaz and Kal?nkara) at the harvest season of 1996. The dried nuts were stored shelled and unshelled in polyethylene bags at 21C and 60–65% relative humidity for 12 months. During storage, the total fat content increased, the palmitic and oleic acid content of the oil increased, linoleic acid, ranged from 12.41 to 10.35%. No significant differences were found for other fatty acids during storage. The effect of storage of shelled and unshelled hazelnuts on the total fat content was significant.     

基于机器学习的维吾尔文文本分类研究

随着Internet上维吾尔文信息的迅速发展,维吾尔文文本分类成为处理和组织这些大量文本数据的关键技术。研究维吾尔文文本分类相关技术和方法,针对维吾尔文文本在向量空间模型（VSM）表示下的高维性,采用词干提取和IG相结合的方法对表示空间进行降维。采用基于机器学习的分类算法（kNN和Na?ve Bayes）对维吾尔文文本语料进行了分类实验并分析了实验结果。     

Simplified mathematical model of proton exchange membrane fuel cell based on horizon fuel cell stack

This paper presents a simplified zero-dimensional mathematical model for a self-humidifying proton exchange membrane（PEM） fuel cell stack of 1 k W.The model incorporates major electric and thermodynamic variables and parameters involved in the operation of the PEM fuel cell under different operational conditions.Influence of each of these parameters and variables upon the operation and the performance of the PEM fuel cell are investigated.The mathematical equations are modeled by using Matlab–Simulink tools in order to simulate the operation of the developed model with a commercial available 1 k W horizon PEM fuel cell stack（H-1000）,which is used for the purposes of model validation and tuning of the developed model.The model can be extrapolated to higher wattage fuel cells of similar arrangements.New equation is presented to determine the impact of using air to supply the PEM fuel cell instead of pure oxygen upon the concentration losses and the output voltage when useful current is drawn from it.     

LoRa在电子价签系统中的应用与实现

传统无线局域网组网方式存在通信距离近、功耗高等问题,不能满足大型超市电子价签系统的通信要求。为此,提出一种基于LoRa(Long Range)通信技术的电子价签系统设计方案。采用具备LoRa调制方式的SX1278芯片作为系统LoRa模块的主芯片,以STM32单片机作为网关和节点价签的主控MCU,采用星型拓扑结构组网,并通过对通信过程中信噪比和接收信号强度两个参数值进行融合计算来分析信道状态,以此实现对数据传输速率的自适应调整。经实验测试,该系统通过服务器可经LoRa无线网络稳定传输数据,最终对电子价签显示内容进行更改,并有效提高了通信距离和降低功耗,可满足大型超市的实际需求。