Advances in radio frequency pasteurisation equipment for liquid foods: a review

Radiofrequency (RF) heating is an alternative emerging technology to conventional thermal methods; it has been employed for food pasteurisation, providing fast and volumetric heating. However, non-uniformity in the heating pattern has been reported. RF pasteurisation has been studied in different liquid foods. This review provides information about the RF heating mechanism and equipment used to pasteurise liquid food to control deteriorative or pathogen micro-organisms and the effect of the RF treatment on the quality of liquid foods. Developing an effective RF pasteurisation for liquid foods requires knowing the food dielectric properties, which determine the heating uniformity, temperature distribution and heating rate. The efficiency of continuous RF heating systems could depend on the fluid rate, resident time and absorbed power. RF heating can pasteurise liquid food, decrease microbial population and preserve the product's nutritional and physicochemical quality.     

Preparations and characterizations of Ca doped Ni–Mg–Mn nanocrystalline ferrites for switching field high-frequency applications

Ca-doped Ni–Mg–Mn spinel ferrites with compositions of Ni_0·5Mg_0·3Mn_0.2Ca_xFe_2-xO₄ (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) were prepared via sol-gel auto-ignition technique. TGA/DTA, FTIR, XRD, FESEM, and VSM were employed to evaluate the thermal, spectral, structural, morphological, and magnetic features of Ca-doped Ni–Mg–Mn spinel ferrites. TGA/DTA curves show the weight loss in the sample. This weight loss was attributed to the oxidation and decomposition of the sample contents at a temperature of 500 °C. XRD reveals a single-phase structure of the Ni–Mg–Mn nano ferrites. A single-phase orthorhombic structure was confirmed for Ca-doped Ni–Mg–Mn ferrites. Structural parameters such as lattice parameter, ‘da’, ‘db’, ‘dc’, and ‘dv’ were evaluated using unit cell software. The absorption peaks at 427 to 538 cm^?1 confirmed the spinel structure, which was evaluated using FTIR. FESEM analyses showed that the agglomerations increased with the doping of Ca in Ni–Mg–Mn ferrites. Remanence, Y–K angles, saturation, coercive force, magnetic squareness, magnetic moment, and anisotropy constant were determined for Ca-doped Ni–Mg–Mn spinel ferrite samples. It is noticed that saturation increases from 29.157 to 51.322 emu/g, whereas remanence increased from 5.34 to 9.40 emu/g, respectively. The permeability, anisotropy constant, and magnetic moments were also found to increase with Ca doping. However, the Y–K angles increased with Ca concentration in Ni–Mg–Mn nano ferrites. In addition, the switching field distribution (SFD) and high-frequency response of all the Ca-doped Ni–Mg–Mn samples were also evaluated. Ca-doped Ni–Mg–Mn samples are suggested to be suitable for switching, filters, inductors, and microwave absorption applications because of the superparamagnetic nature of the prepared spinel ferrites.     

C105管桩混凝土设计参数取值的探讨

通过试验得出了C105混凝土100 mm×100 mm×100 mm立方体非标准试件抗压强度换算系数以及C105混凝土的标准方差和强度变异系数。采用理论计算,得到了棱柱体抗压强度与立方体抗压强度的比值α_c1,并与试验实测平均值进行了比较,验证了理论计算方法的可行性。此外,通过对比分析,探讨了直接外延法和引用公式法两种C105混凝土设计参数计算方法的正确性,研究结果可为C105管桩混凝土的设计和应用提供参考。     

Simulation based neuro-fuzzy hybrid intelligent PI control approach in four-area load frequency control of interconnected power system

This paper presents a novel control approach of hybrid neuro-fuzzy (HNF) for load frequency control (LFC) of four-area power system. The advantage of this controller is that it can handle the non-linearities, and at the same time it is faster than other existing controllers. The effectiveness of proposed controller in increasing the damping of local and inter area modes of oscillation is demonstrated in four area interconnected power system. Area-1 and area-2 consist of thermal reheat power plant whereas area-3 and area-4 consist of hydro power plant. Performance evaluation is carried out by using fuzzy, ANN, ANFIS and conventional PI and PID control approaches. The performances of the controllers are simulated using MATLAB/Simulink package. The result shows that intelligent HNF controller is having improved dynamic response and at the same time faster than ANN, fuzzy and conventional PI and PID controllers.     

红枣多糖的高压脉冲电场高效提取及其在卷烟中的应用

采用UV-Vis分光光度法测定红枣中多糖含量,考察了红枣多糖的高压脉冲电场高效提取及工艺优化,并进行了卷烟加香试验。通过分析高压脉冲电场强度、温度、液料比、脉冲频率4个因素对多糖提取率的影响,在单因素试验结果的基础上,设计正交试验。试验结果表明：最佳测定条件为A2B3C2D2,即高压脉冲电场强度为20 kV/cm、固定高压脉冲电场温度为100℃、液料比为15∶1（体积/质量）、脉冲频率为10000 Hz。该方法快速、灵敏、准确,可用于红枣多糖的高效提取,最佳提取工艺条件下的提取率为3．01％。红枣多糖的卷烟加香试验表明,其能增加卷烟香气中的烤甜香韵,醇和烟气,改善口感。     

大型原点反共振振动筛的初步设计

针对传统大型振动筛筛箱侧帮易断裂,参振质量大,隔振效果差等问题,提出了将反共振理论用于振动筛的设计理念,建立了反共振振动筛的力学模型,并进行动力学分析,得到筛箱和下质体稳态时的响应振幅,通过绘制双质体系统的幅频特性曲线得到反共振振动筛的激振频率。利用Solidworks软件对反共振振动筛进行三维建模,完成了大型原点反共振振动筛的初步设计。结果表明:可调激振器位置的斜面设计使激振力通过上质体质心,保证了筛箱的正常工作。由圆柱形螺旋弹簧组成的弹簧座连接上、下质体及地面,保证了系统所需弹性系数;通过应用PID控制技术监控上下质体振幅,并改变激振频率来稳定上、下质体振幅,实现原点反共振振动筛振幅的稳定性控制。     

TBS分选机在王家岭选煤厂的应用

阐述了TBS分选机的工作原理和技术参数。分析了两种TBS分选机入料及产物的粒度和密度组成,对比了两种TBS分选机的分选精度。结果表明:两种TBS分选机的入料粒度组成类似,0.2~1.0 mm质量分数大于60%,属主导粒级,适合采用TBS分选机分选,其精煤灰分均小于10%,尾煤灰分均高于57%,分选效果较好。当精煤灰分为9.50%时,两种TBS分选机的入料煤样均属易选煤。两种TBS分选机的Ep值分别为0.178和0.183,I值分别为0.239和0.246,分选效果基本相同,均达到较高水平,分选下限达到0.2 mm。