冷链条件下气调包装酱卤鸭肉制品货架期预测模型的建立

目的 以气调包装酱卤鸭肉制品为研究对象,在冷链温度范围内建立一套准确、高效的货架期预测模型。方法 利用选择性培养基测定不同温度下产品各微生物数量,确定4~25℃条件下产品优势腐败菌。对乳酸菌数量与感官评定值进行了回归分析确定最小腐败量Ns。分别采用修正的Gompertz方程和平方根方程建立一、二级模型,并通过预测值与实测值对比验证模型的可靠性。结果 确定了4~25℃条件下产品优势腐败菌为乳酸菌,最小腐败量Ns=6.14(lg(cfu /g))。一、二级模型拟合度均良好,三种温度下模型预测值与实际值间的差异均在30％左右,波动幅度在10%以内。结论 实现了对4~25℃内任何时间点产品剩余货架期的预测,为冷链条件下气调包装酱卤鸭肉制品品质的变化提供了理论指导。     

加氢反应器内构件—急冷箱的试验研究

急冷箱是加氢反应器的重要内件。洛阳石化工程公司设备研究所在认真分析UOP急冷箱的基础上,对其结构进行了改进,开发出了新型急冷箱(已获专利)。经过流体力学、传质、传热性能对比试验、分析,新型急冷箱结构性能优良。     

Effect of advanced chilling methods on lipid damage during sardine (Sardina pilchardus) storage

Slurry ice is a biphasic system consisting of small spherical ice crystals surrounded by seawater at subzero temperature. Its effect on lipid damage (hydrolysis and oxidation) was evaluated during the chilled storage of a fatty fish species, sardine (Sardina pilchardus). Slurry ice treatment was checked alone and in combination with ozone and compared to traditional flake icing during a 22‐day storage. Different lipid damage indices (free fatty acids, FFA; peroxide value, PV; thiobarbituric acid index, TBA‐i; fluorescent compounds, FR) were checked and compared to sensory assessment and nucleotide degradation (K value). According to lipid hydrolysis (FFA) and oxidation (PV and FR) developments, slurry ice showed an inhibitory effect (p <0.05) on lipid damage during storage, as well as an inhibition of nucleotide autolytic degradation. Ozonised slurry ice did not provide differences (p >0.05) from slurry ice alone when considering lipid hydrolysis, nucleotide degradation and some lipid oxidation indices (PV and FR), although a higher (p <0.05) TBA‐i was observed at day 22 of storage when compared to flake ice and slurry ice treatments. However, a lower (p <0.05) fluorescence development was observed for fish treated under ozonised slurry ice when compared to traditionally iced fish. Sensory assessment showed a higher shelf life for fish samples treated under ozonised slurry ice than for their counterparts under slurry ice (15 d versus 12 d), while flake icing led to a far shorter shelf life (5 d). According to sensory and biochemical (lipid matter and nucleotide) analysis, slurry ice has proved to be a promising technology for damage inhibition and quality retention in a fatty fish species such as sardine. Ozonised slurry ice was also shown to be useful, since a longer shelf life was obtained in the present experiment and a pro‐oxidant effect of ozone on sardine lipids was not proved.     

异程管网热湿负荷分配次优解群及适应性

提出了一种基于次优解群统计分析的异程管网热湿负荷分配方法,采用变步长+随机走步的寻优计算方法,获得空调季不同负荷率下热湿负荷再分配的次优解群,分析次优解群的随机行为和统计规律,以此探索复杂变量约束下的冷冻水系统负荷分配的优化控制策略及其适应性。根据计算结果,在40%、60%、80%、100%这4种负荷率下末端人数次优解重叠率最高达到24%。研究表明,次优解群随机行为与管网热湿负荷分配策略存在相关性,离冷源侧越近,末端人数次优解重叠率越高,分配策略的负荷适应性越好,其权重越大。     

凸轮轴激冷面气孔成因及防止方法的探讨

详细分析了神龙富康轿车冷硬铸铁凸轮轴激冷面气孔产生的部位和原因，从控制原材料、加强型腔排气、改进浇注系统、加强冷铁质量管理等方面采取措施，使激冷面气孔明显减少。     

Experimental investigation on chilled cast iron tappet manufacturing processes parameters

Chilled cast iron tappet has a tendency microstructure of white, mottled and gray iron. The exact composition and other casting parameters, like pouring temperature, inoculation and coating, need to be determined for achieving the desired thickness of the chilled layer. Chilled cast iron finds applications in areas where improved hardness and wear resistance are required. Mottled cast iron has very poor machinability and high brittleness due to the presence of secondary cementite. These constitute the limitations for its use. The influence of inoculation, pouring temperature, coating thickness and chill plate on chilled depth was investigated. Taguchi design-of-experiments (DOE) are used for generating an optimal set of casting parameters to obtain a satisfactory chilled depth. Analysis of the effects of all the parameters on chilled depth has been carried out through a microstructure study.     

不同品系北京鸭血清前白蛋白多态性的研究

应用聚丙烯酰胺凝胶电泳法研究了北京鸭的血清前白蛋多态性,在2个位点观察到多态,Pam位点为单态,在Pas位点发现有5种表现型,它们的频率是：Pas2-2O 26．67％,Pas1-2为12％,Pas2-1为45.33%,Pas1-1为2．67％,Pas2-0为13．33％,在Paf位点发现有4种表现型,它们的频率是：PafF为29．33％,PafS为41．33％,PafFS为10．67％,Paf0为18．67％,并计算了它们的基因频率,群体平均杂合度和遗传距离,遗传分析表明,樱桃谷鸭和奥白星鸭遗传结构相似,而与B系北京鸭遗传结构有明显差异。     

中央空调冷冻水系统的专家PID 控制

对于具有非线性、大滞后和时变性的中央空调冷冻水系统,根据专家经验设计了专家PID控制器.MATLAB仿真研究表明,专家PID控制器同常规PID控制器相比,具有较高的动态特性,能够达到理想的控制效果.     

以茶多酚为主体的抗氧化剂联用对冷却肉保鲜作用的研究

研究了茶多酚及其分别与维生素E(VE)、维生素C(VC)、(VE VC)联用对冷却肉的保鲜作用,探讨了各组抗氧化剂的保鲜机理.结果表明:茶多酚对冷却肉具有显著的保鲜效果,它与Vε、VC、(VE VC)联合使用时有增效作用.保鲜效果顺序为:茶多酚 VC VE＞茶多酚 VE＞茶多酚 VC＞茶多酚＞对照组.     

大温差空调水系统的技术经济分析

空调水大温差技术是一项节能技术,但有其适用场合.本文从水泵能耗减少和冷水机组能耗增加两方面进行对比,得到了大温差技术的适用对象,并从初投资和运行费用两方面对大温差技术进行技术经济分析,提出简单实用的计算方法.