Direct Synthesis of Diphenyl Carbonate with Heterogeneous Catalyst and Optimal Synthesis Conditions of the Support Prepared by Sol-gel Method

The support of catalyst for the direct synthesis of diphenyl carbonate （DPC） by heterogeneous catalytic reaction was prepared by the sol-gel method. Compared with activated charcoal, molecular sieve, porous ceramics, hopcalite, the support prepared by the sol-gel method has higher activity. The characterization of the support by X-ray diffraction （XRD） and transmission electron microscope （TEM） show that the mare crystal phase is Co2MnO4 and the average particle diameter is about 40 nm. The optimum conditions for synthesis of the support were determined by orthogonal experiments, which indicate that the proportion of Cu, Mn, and Co is the first important factor influencing the yield and selectivity of DPC. Temperature of calcination is the second one. The optimum conditions are： molar proportion of Cu, Mn, and Co being 1 ： 1 ： 1, temperature of calcination 700℃, drying at 100~C, temperature of water bath 85~C. The yield and selectivity of DPC in the process can reach 38% and 99% in the batch operation, respectively. The copper cobalt manganese mixed oxides chosen as the support contribute more to the high catalytic activity than the sol-gel method.

Study on Direct Synthesis of Diphenyl Carbonate with Heterogeneous Catalytic Reaction (V) Screening Catalysts and Optimizing Synthesis Conditions

Pd/LaxPbyMnOz, Pd/C, Pd/molecular sieve and Pd-heteropoly acid catalysts for direct synthesis of diphenyl carbonate (DPC) by heterogeneous catalytic reaction were compared and the results of DPC synthesis indicated that the catalyst Pd/LaxPbyMnOz had higher activity. The Pd/LaxPbyMnOz catalyst and the support was characterized by XRD, SEM and TEM, the main phase was Lao.szPbo.asMnOa and the average diameter could be about 25.4nm. The optimuna conditions for synthesis of DPC with Pd/LasPbyMnOz were determined by orthogonal experiments and the experimental results showed that reaction temperature was the first factor of effect on the selectivity and yield of DPC, and the concentration of O2 in gas phase also had significant effect on selectivity of DPC. The optimum reaction conditions were catalyst/phenol mass ratio l to 50, pressure 4.5MPa, volume concentration of O2 25%, reaction temperature 60℃ and reaction time 4 h. The maximum yield and average selectivity could reach 13% and 97% respectively in the batch operation.

Herbicidal activity of Aureobasidium pullulans PA-2 on weeds and optimization of its solid-state fermentation conditions

Fungal strain PA-2 was isolated from infected poplar leaves from the Ping’an District, Haidong City of Qinghai Province, China. Based on the culture characteristics and the internal transcribed spacer(ITS) sequence of its 16S r DNA, the strain was identified as Aureobasidium pullulans. The culture and metabolites of strain PA-2 showed high herbicidal potential to five tested weeds Galium aparine var. tenerum, Chenopodium album, Malva crispa, Polygonum lapathifolium and Avena fatua. For the in vitro test, 5 days after the detached leaves were inoculated with PA-2 culture, all leaves infected by the hyphae and became black and rotten. For the in vivo test, a metabolite filtrate of PA-2 culture was sprayed over the living weed plants, and five days after inoculation, the weed plants became withered and necrotic. Seven days after inoculation, the fresh weight reductions of G. aparine var. tenerum, C. album, M. crispa, P. lapathifolium and A. fatua were 87.25, 78.46, 82.25, 62.11, and 80.27%, respectively. Galium aparine var. tenerum and M. crispa exhibited significant reductions in fresh weight. The bio-safety test on the five crops showed no significant plant height reductions, which was also observed for wheat(Triticum aestivum), faba bean(Vicia faba), and barley(Hordeum vulgare). By contrast, oilseed rape(Brassica napus) and pea(Pisum sativum) exhibited light spots but no significant reductions in plant height. These results indicated that A. pullulans could be a potential microbial herbicide for the control of the target weeds in crops. Optimization of the carbon and nitrogen sources for cultural media and substances for solid-state fermentation indicated that PA-2 had better colony growth and spore production with the optimal carbon source of glucose(C4), nitrogen source of soybean flour(N2), and the optimal substance was wheat bran. The results in this study provide useful information for the development ofA. pulluans PA-2 as an herbicide for bio-control of the weed.

An Experimental Study on Optimization of Large-volume Airgun Source Excitation Conditions in a Reservoir

Through manual pickup of seismic phases,the number of recording stations,the farthest observation distance of station and received energy are determined,then optimal operating condition processing software is developed to evaluate the excitation effect of operating conditions. The optimal operating conditions in the Mianhuatan Reservoir are determined using this software. They are: optimal water depth 25 m,airgun array sink depth 9m and airgun array size 7m × 7m. At the same time,accumulative stacking results for every 10 times are analyzed for 300 fixed-point excitations. It is concluded that the excitation effect shows a rapidly rising trend at 10 to 90 times stacking,a slowly rising trend at 100 to 150 times stacking,a rapidly rising trend at 160 to 240 times stacking,and a slowly rising trend at 250 to 300 times stacking. As the number of stacking increases,the propagation distance and the number of recording stations also increase gradually.

中小型水面舰船空调系统设计研究

阐述水面舰船空调系统的功能和基本形式,介绍核生化防护对空调系统的设计要求和当前舰船空调系统设计中存在的一些问题。通过对中小型水面舰船空调系统设计特点的分析,提出空调系统设计的新概念对空调设备的要求。

变频空调系统特性的仿真研究

用仿真的方法着重研究了变频空调系统偏离最佳工况运行时的系统各参数特性。

UPQC输出滤波器的优化设计

在考虑负载特性对输出滤波器影响的基础上,建立了统一电能质量控制器(UPQC)中输出滤波器的数学模型,分析并指出串并联单元的输出滤波器之间存在相互耦合的关系。以此为基础,提出了一种实用的输出滤波器参数优化设计方法,综合考虑串并联单元输出滤波器的特性和谐波电流跟踪的要求,以低频段和高频段的衰减特性最优化为目标函数,运用蚁群优化算法对UPQC输出滤波器的参数进行优化设计。仿真结果表明,与传统的方法根据经验设计的参数相比,采用优化参数后的输出滤波器能够有效减小补偿误差,改善UPQC的补偿效果。

带施香、消臭、杀菌功能的节能型家用空调器的研制

作者采用微机优化设计程序得出了空调器各部件参数，并经实验确定了各部件的匹配及有关的最佳参数，所研制的三种系列空调器能效比（ＥＥＲ）分别达到３．２７，３．１４，３．４０。该空调器还具有独特的施香和紫外线杀菌功能。

家用空调制冷剂充注量与毛细管长度的匹配

通过试验的方法研究了空调器制冷剂充注量与毛细管长度对制冷系统的影响,得出了相应的试验曲线,找出了最佳匹配结果.根据试验结果分析了毛细管长度与制冷剂充注量影响空调性能的基本规律.

变频空调器除湿量的试验研究

本文以试验数据为基础,得出了变频空调器除湿模式下除湿量与进风状态、风量、压缩机运转频率的关系,为优化变频空调器除湿模式的运行参数提供了初步依据。

热回收型空调器的优化设计及经济分析

阐述热回收型空调器优化设计的目的,即获得最大的经济效益。论述优化设计中影响经济指标的各种因素,并以实例说明优化设计中应注意的问题。分析建筑低品位能源的回收利用,对热回收型空调器的实例做了节能分析与经济分析。

家用半导体空调器的优化设计

阐述了家用半导体空调器的优化设计 .通过合理匹配半导体电堆 ,使空调器处于最佳化运行电流状态 。

一种新型统一电能质量控制器设计原理及控制方法

首先详述了基于不同控制策略(电压同相位补偿UPQC-P以及最小输出视在功率UPQC-VA下,统一电能质量控制器UPQC(unified power quality conditioner)的输出视在功率及其容量设计;然后提出一种新型UPQC设计方法和相应的控制算法以优化UPQC设计容量,提高UPQC容量利用率;最后,详述了该算法原理,通过基于所提算法以及UPQC-P、UPQC-VA算法的UPQC容量设计、UPQC利用率大小的对比分析,有效证明了该控制算法的优越性。

三相并联有源滤波器的新型复合控制方法

PI控制方法具有理论简单、易于实现和动态响应快的优点,广泛应用于控制系统中。单独的PI控制方法应用于谐波补偿虽具有很好的动态响应,但其稳态精度不高。为提高谐波补偿的稳态精度,探讨一种基于PI控制与重复控制串联的复合控制方法,并对其谐波补偿性能进行仿真研究。结果表明,串联复合控制具有较好的谐波补偿稳态精度,证明该方法的正确性与可行性。

家用变频空调充注优化过程各参数的研究

为了研究制冷剂充注量的变化对家用变频空调器性能的影响,进行了不同充注量实验。根据实验数据分析了充注量对蒸发器、冷凝器、液相管、气相管的压降以及对系统运行功率、蒸发压力、冷凝压力和系统性能系数(COP)等的影响,并且提出了一个判断系统最佳充注量依据。研究结果对变频空调器的设计优化和充注优化起到了一定的参考价值。

EXTRACTION OF ANTHRAQUINONE DERIVATIVES FROM RHUBARB RHIZOMES AND THEIR ANTIBACTERIAL TESTS

Photometry was employed to study the optimum extraction conditions of anthraquinone derivatives from rhizomes of Rheum officinale Baill in this study.The influences of extraction solvents(chloroform,benzene,ethanol,methanol,and glycerol),acid,and extraction time on the extraction yield were discussed.The results indicate that,to the Rhubarb rhizomes powder with the average particle size 0.18 mm,the conditions of the extraction solvent composed by chloroform,glycerol,and sulfuric acid(20%)in the ratio of 4:1:1(v:v),the weight of dried Rhubarb to the solvent volume in the ratio of 1:12 ew:vT,extraction time of 110 min,the anthraquinone derivatives extraction could achieve the best yield.And the antibacterial tests showed the raw extraction products had the MIC(minimal inhibitory concentration)of 20μg=mL and 30μg=mL to Staphylococcus aureus and Escherichia coli,respectively.

R410a新工质转子压缩机在房间空调器的应用

本文结合R410a制冷剂的特性,对某公司一款房间空调器系统进行了利用R410a替代HCFC22的应用实践,进行了理论分析和系统匹配。实验结果表明,在相同条件下,相对于HCFC22,换热系数提高,流动阻力下降,通过系统优化匹配设计后,性能(COP)得到大幅提高,达到欧洲市场A级能效等级。R410a新冷媒压缩机在空调器的搭载应用实践为R410a压缩机的推广使用奠定了基础。

A Good GC Stationary Phase for Separation of Xylene Isomers

An excellent separation of xylene isomers is reported using 2, 6-O-di-pentyl-3-O-acetyl-beta-CD as capillary stationary phase. The optimum conditions for the separation are also discussed.

Optimization of Extraction and Characterization of Pectin from Grapefruit Peels

In this study, pectin was extracted from grapefruit peels with hydrochloric acid and precipitated with 95% ethanol solution and 5% tartaric acid. The physical and chemical properties of pectin obtained were analyzed, including color, texture, degree of esterification, and water solubility. The effects of peel to sol- vent ratio, pH of the solvent, extraction temperature and extraction duration on pectin extraction rate were investigated. On the basis of single-factor experiments, an L9 （34） orthogonal experiment was performed to screen the optimal extraction conditions. According to the results, the optimal combination of technical parame- ters was A1B3 C1 D3, i. e. , solid to liquid ratio 1：40 （g： ml）, pH 2.0, extraction duration 70 rain, extraction temperature 90 ℃. The average pectin extraction rate was 68.60% ; the color of pectin extracted under the optimal conditions varied from milky white to light yellow; the degree of esterification of pectin extracts was 65. 71% ; the extracted pectin exhibited good water solubility. Key words Pomelo peel; Pectin extraction; Optimum conditions; Esterification degree; Water solubility

THE STATISTIC ANALYSIS OF SCREEN PARAMETERS ON PERFORMANCE CHARACTERISTICS

A series of laboratory screening tests have been performed with the objective of evalu-ating the effect of feed rate, screen length and screen motion on the quality of separation achieved. The statistic analysis and results derived from it are discussed. Suggestions for future work with the objective of assessing the industrial significance of the research to the optimisation and design of screening processes are presented.