火龙果果皮色素的提取及稳定性

采用不同比例的水与乙醇混合液作为提取剂、不同的超声波提取时间、不同的火龙果果皮重量,研究了火龙果果皮色素的提取条件。其提取液最大吸收波长在538nm处,长时间放置后色素被氧化,其氧化产物最大吸收波长在390nm处。还研究了火龙果果皮色素与食品添加剂共存的情况。     

冷藏运输车内气体流场的数值模拟及分析

利用计算流体力学(ANSYS)软件,建立了冷藏运输模拟试验台的物理模型,对冷藏运输车内流场进行了数值模拟研究。主要研究内容包括:(1)不同送风速度对冷藏运输车内流场分布的影响;(2)不同时间内库内流场变化情况。冷藏运输模拟试验台采用前端送风,两侧回风口的送风方式。风机吹出的冷气能够在库体内形成大的回流,从而降低库体温度并且使库体内温度分布的均匀。不同送风速度影响车体内速度场的分布,而当送风速度较大时,库内的温度会在短期内均匀。但是过大的送风速度会风干冷藏车内的食品。     

冷藏汽车制冷方式及其特点

冷藏汽车在易腐食品产、贮、运、销中起着重要的作用,文中分析了我国食品冷藏链的现状,介绍了冷藏车的发展概况,阐述了冷藏汽车在食品链中的作用和地位,系统论述了冷藏汽车的各种制冷方式及其特点,介绍了冷藏汽车的技术状况。提出了发展我国冷藏车的建议,对我国冷藏车的设计与运行管理具有一定的参考价值。     

三门冷藏展示柜的系统设计

随着冷柜市场的不断细分以及零售业市场的快速发展,为迎合市场需求实现多门冷藏柜的系列化开发,针对性设计了一种三门冷藏展示柜,以风冷作为制冷方式,采用风冷压缩式制冷系统。其中包含冷柜结构、制冷系统、电控系统的设计。通过热力计算得到:在冷凝温度42℃,蒸发温度0℃工况下,其热负荷为1 143.56 W,并对压缩机、冷凝器、蒸发器等部件进行了设计选型。实践证明,该冷柜具有展示效果好,制冷性能稳定等特点。     

冷藏陈列柜热工性能实验室设计

对冷藏陈列柜测试室进行设计,参照GB/T 21001.2 - 2007和EN441 -2标准,测试室全自动控制运行,操作方便,设计方案满足了用户的需求.     

冷藏集装箱内部温度场的理论与实验研究

冷藏集装箱内部的温度分布是冷藏集装箱设计中关注的要点,因此文中通过建立冷藏集装箱物理模型和数学模型对其温度场进行了数值模拟和实验研究。利用稳态不可压缩N-S时均方程及k-ε模型进行模拟分析,结果表明:冷藏集装箱内部温度场存在明显的不均匀性,箱体前部与后部的温度存在明显的差异,不利于货物的储存。实验实测温度与模拟温度的偏差低于16.4%,说明所建立的模型适用于冷藏集装箱内部温度场的模拟。研究结论对进一步开展冷藏集装箱货物配载以及结构设计研究具有一定的指导与借鉴意义。     

食品冷藏运输过程的LCCP评价

本文基于寿命期气候性能LCCP概念,加入环境温度变化、冷藏运输车型、车速、制冷柜的COP和驱动方式、运输距离等影响因素,提出了科学评价食品冷藏运输过程LCCP的计算方法,并对12种冷藏运输车,在六个城市、不同冷藏温度及不同寿命期限内,使用R404A、R410A、CO₂三种制冷剂的LCCP进行了对比评价。结果表明:环境温度较高的城市,LCCP较大;与CO₂及R410A相比,R404A的LCCP最大;冷藏温度越低,能耗越大,LCCP越大;相比于使用主发动机或电驱动制冷柜的冷藏车,使用辅助发动机驱动的冷藏车的LCCP较大。     

货物堆码方式对冷藏集装箱内温度分布的影响

为了研究货物堆码方式对冷藏集装箱内温度分布的影响,以20英尺冷藏集装箱为研究对象,建立箱内空气对流与换热的物理和数学模型。采用标准k-ε紊流计算模型,对稳态下的箱内温度分布情况进行模拟仿真。在装载货物量不变的情况下,通过改变冷藏货物的配载方式,采用CFD软件模拟了箱内温度场分布。结果表明:货物左右对称装载方式的温度场分布情况优于货物整体装载方式;合理的控制货物转载高度、货物与箱壁侧面间隙可以有效防止湍流现象的发生。     

冷藏集装箱内部流场及送风方式的研究

冷藏集装箱内部流场的均匀性是影响货物储存质量的重要因素之一。文中通过建立CFD三维数学模型,利用FLUENT软件对所建立的模型进行不同参数的模拟分析。分析结果表明:冷藏集装箱内部流场存在明显的不均匀性,箱体前部与后部的温度存在明显的差异,不利于货物的储存。根据以上分析研究,利用均匀送风理论,设计出两种新型送风风道型式,根据对所设计的风道进行计算分析,研究发现:新型冷藏集装箱与原始冷藏集装箱相比温度场和速度场都有明显改进,且在箱体中部的流场涡流现象减小,有利于货物的储存,该研究为冷藏集装箱的优化设计提供了参考依据。     

立体仓库用风冷式冷藏保温箱实验研究

本文对风冷式冷藏保温箱送风过程进行实验研究,采用热源法测试冷藏保温箱漏热系数,冷藏保温箱内和门封四周的温度变化,建立降温时间模型,计算冷藏保温箱最佳送风量。结果表明:冷藏保温箱从环境温度降到0℃的时间,计算与实验结果的最大误差为6.93%,平均误差为5.77%;从2℃降到0℃时间的最大误差为6.15%,平均误差为5.28%,其计算模型精度较高。冷藏保温箱降温时间随送风量的增加而减短,且降温时间的减小幅度越来越小,综合考虑降温时间和初投资,送风量选择0.021m~3/s比较合适;由于门封四周密封不均匀,门封测点12#处温度最低,环境温度为10、20、30℃时,其结露临界相对湿度分别为64.4%、64.9%、52.1%,阴雨天气门封结露的可能性较大。     

Improvement of betalains stability extracted from red dragon fruit peel by ultrasound-assisted microencapsulation with maltodextrin

Natural betalains can be potential food additives because of their antioxidant activities, but they have poor thermal stability. In this study, betalains were extracted from red dragon fruit peel, and then encapsulated with maltodextrin by ultrasound method to increase the physicochemical properties of betalains microcapsules. The encapsulation efficiency of the betalains was above 79%, and the particle size and Zeta potential values were 275.46 nm and −29.01 mV, respectively. Compared to the control sample, onset temperature and DPPH free radical scavenging of betalains microcapsules under the modest ultrasound treatment (200 W, 5 min) was increased by 1.6 °C and 12.24%, respectively. This increase could be due to the ability of ultrasonification to create interactions between maltodextrin and betalains (as evidenced by FT-IR). Therefore, modest ultrasound treatment can be used for microcapsulation to improve the stability of betalains, and then expand the application of betalains in heat processed food field.     

无损检测技术在水果品质评价中的应用

介绍了声、光、电、射线等物理学技术在水果品质无损评价NDE(nondestructive evaluation)中的应用，分析了这些技术在水果生产、分选、采后加工等过程中的应用价值，指出必须加强无损评价技术在果品品质评价方面的应用，以物理学高新技术的发展推动农业经济的持续发展．     

冷却物冷藏间冷风机的空气除霜实验研究

冷却物冷藏间以贮藏果蔬为主,当贮藏品种产于热带地区,贮藏温度高于0℃。由于贮藏温度距水的冰点不远,制冷系统的蒸发温度会低于冰点,在工作过程中蒸发器表面必然结霜。文中对冷间温度高于冰点,蒸发温度低于冰点的冷库制冷系统,进行了空气除霜和"依次除霜法"实验,通过冷风机回风区空气温度、冷风机蒸发管组翅片温度的测量,结合肉眼观察认为,库温为5℃的情况下,依靠制冷压缩机停机阶段,冷风机风扇常开,能够基本除掉上次制冷过程产生的结霜,当制冷系统规律工作8小时,前期制冷过程积累的结冰可以通过"依次除霜法"依次关闭除霜冷风机的供液电磁阀15分钟,在保证库房降温的前提下,能够彻底除掉蒸发器表面的结霜。     

Thermoultrasound and microwave-assisted freeze-thaw pretreatments for improving infrared drying and quality characteristics of red dragon fruit slices

The effects of thermoultrasound (US-FT), microwave (MW-FT), and room temperature (RT-FT) freeze–thaw pretreatments were evaluated for improving drying kinetics and quality during infrared drying (IRD) of red dragon fruit slices (RDFS). Results indicated that microstructural alterations induced by the different pretreatments improved the moisture removal rate and effective diffusivity, and significantly reduced the drying time. US-FT pretreatments prompted more efficient drying and presented an overall enhancement in the quality of RDFS, particularly at low temperatures of 25 and 50 ℃, while enhancements in TFC, FRAP, and CUPRAC were associated with RT-FT. High-power (500 W) MW-FT pretreatments improved colour and structural properties, while low-power (100, 300 W) improved TPC, TFC, ascorbic acid, betalains, and antioxidant activity. Overall, cellular and chemical alterations prompted by pretreatments improved the drying process but presented adverse effects on betaxanthin. The study presented the fundamental background for improving the IRD of foods from the use of improved thawing approaches during freeze–thaw pretreatments.     

Current situation and industrialization of Taiwan nanotechnology

Nanotechnology is projected to be a very promising field, and the impact of nanotechnology on society is increasingly significant as the research funding and manufactured goods increase exponentially. A clearer picture of Taiwan’s current and future nanotechnology industry is an essential component for future planning. Therefore, this investigation studies the progress of industrializing nanotechnology in Taiwan by surveying 150 companies. Along with understanding Taiwan’s current nanotechnology industrialization, this paper also suggests ways to promote Taiwan’s nanotechnology. The survey results are summarized and serve as the basis for planning a nanotechnology industrialization strategy.     

Stable isotopes determination in some Romanian fruit juices

The characterisation of 45 Romanian single-strength fruit juices (apples, pears, plums and grapes) collected from different Transylvanian areas by means of stable isotope approach are presented and discussed in this study. We measured ²H/¹H, ¹⁸O/¹⁶O ratios from water juice and ¹³C/¹²C from pulp and compared these results with those already reported in the literature for single-strength juices, in order to see how the geographical and climatic conditions of Transylvania and the meteorological peculiarities of the year 2010 influence the isotopic composition of the investigated fruit juices. The δ¹³C mean values that we found for apple pulp picked up from different Transylvanian areas show slight differences, probably due to the environmental conditions of the plants. No significant correlation either between the variety of apple or the geographical origin and δ¹³C value was established.     

Storage of intense optical pulses in solids

Possibility to store optical information in media with fast relaxations is studied in case of arbitrary intensities of probe and control pulses. Analytical solution of the self-consistent system of equations for propagation and density matrix is obtained with allowance for the first non-stationary corrections. A new scheme of storage is proposed which allows an essential reduction of the optical length needed for storage.     

白昼星敏感器的研究现状及关键技术

星敏感器以恒星为姿态测量参考源,可以为空间飞行器提供高精度姿态测量信息。白昼星敏感器具备白昼条件下恒星探测能力,可以拓展用于高空气球、飞机、导弹、舰船等近地空间平台的全天时自主导航。对白昼星敏感器的国内外研究现状进行了综合分析,介绍了典型白昼星敏感器的技术指标,对制约白昼星敏感器发展的技术瓶颈和关键技术进行了梳理和总结。     

四丁基溴化铵水合物浆在蓄冷空调中的应用前景

TBAB水合物浆作为适用于空调工况的新型两相潜热输送载冷剂,可以大幅度降低冷量输送的功耗。通过添加成核剂的方法来降低所需的过冷度,制备方法简单节能,而且蓄冷特性出色,相变蓄冷温度与溶液的浓度密切相关,可通过调节溶液的浓度,获得与空调冷冻水一致的相变温度。根据非牛顿流体的特点,综述了国内外关于TBAB水合物浆流变方程的选择,列出了表观粘度及传热系数的计算方法,并指出TBAB水合物浆应用于蓄冷空调中的优点。