不同贮藏温度下小黄鱼货架期预测模型的建立和评价

目的探究不同贮藏温度下小黄鱼的品质变化与货架期之间的关系,并建立货架期预测模型。方法设计了273,278,283,288,293 K等5组不同温度下的贮藏实验,对小黄鱼的感官品质指标变化、持水率、pH值、色差(L值、b值)、挥发性盐基氮(TVB-N)、菌落总数和鲜度指标(K值)的变化进行测定分析;运用Arrhenius方程对菌落总数、TVB-N、K值与贮藏时间及贮藏温度建立动力学预测模型。结果菌落总数、TVB-N和K值随着贮藏时间的延长而逐渐增加,感官品质随贮藏时间的延长而下降。结论该模型所获得的货架期预测值准确率达到90%以上,可用于温度为273~293 K范围内小黄鱼剩余货架期的预测。     

真空软包装香辣蟹贮藏品质变化及货架期预测

目的研究香辣蟹在常温贮藏条件下的保鲜包装,探究真空软包装香辣蟹的品质变化规律及常温贮藏货架期。方法测定真空软包装香辣蟹在23,33,43℃贮藏环境下的品质指标值,包括菌落总数、质构、pH值及挥发性盐基氮(TVB-N值),并综合感官评价确定真空软包装香辣蟹的货架期终点,利用Arrhenius法预测真空软包装香辣蟹货架期并建立货架期预测模型。结果在23,33,43℃贮藏温度下,真空软包装香辣蟹的挥发性盐基氮含量分别在第21,18,15天达到感官可接受的极限值(分别为29.75,30.21,31.46 mg/(100 g))。结论基于TVB-N值变化建立的货架期预测模型可很好地预测真空软包装香辣蟹的货架寿命。     

鲳鱼复合生物保鲜剂冰的配比优化及保鲜效果

在单一生物保鲜剂研究的基础上,采用两因素三水平正交试验的方法,将不同浓度的茶多酚和植酸进行复配制冰后分组处理新鲜鲳鱼。对鲳鱼品质变化表征特性指标(感官评价),微生物指标(菌落总数),理化指标(挥发性盐基氮含量(TVB-N)、2-硫代巴比妥酸含量(TBA)和K值)进行分析,确定了鲳鱼复合生物保鲜冰的优化配比浓度,并验证其保鲜效果。研究结果表明:用茶多酚0.5%(w/v),植酸0.15%(v/v)的复合保鲜冰使鲳鱼的感官指标、微生物指标、理化指标均优于自来水冰的对照组,在1℃冷藏条件下的货架期由11~12 d延长至21~23 d。     

不同贮藏温度下养殖鲤鱼菌相变化分析

目的通过研究在室温、低温环境下贮藏养殖鲤鱼的菌相、感官、化学和微生物学品质,确定鲤鱼特定腐败菌、货架期和贮藏中鲜度变化,为构建货架期预测模型提供基础。方法分别取贮藏初始和贮藏温度分别为0,5,10,15,25℃货架期终点的鲤鱼鱼肉进行菌落总数、假单胞菌、产H2S菌计数、挥发性盐基氮(TVBN)值测定,并确定特定腐败菌。结果贮藏初始鲤鱼感官指标良好,菌落总数、产H2S菌、假单胞菌和TVBN值分别为(4.34±0.58),(2.85±0.63),(3.42±0.45)lg(CFU/g)和(84.7±5.7)mg/kg。在0,5,10,15℃下贮藏的鲤鱼货架期分别为(28.9±1.20),15.9,6.1,3.6 d,特定腐败菌为腐败希瓦氏菌和假单胞菌;室温货架期为1.1 d,特定腐败菌为气单胞菌。结论基于鲤鱼低温和室温贮藏品质特征、货架期和菌群变化的结果,为货架期模型构建提供了参考。     

不同贮藏温度下冷却肉品质变化的实验研究

考察了不同贮藏温度下(O℃、5℃、10℃和20℃)猪肉细菌总数、挥发性盐基氮、色差、感官评定、pH值随保存时间的变化规律.发现猪肉的细菌总数、挥发性盐基氮值随贮藏时间的延长而增加,随贮藏温度的增加而上升;随着贮藏时间的延长,猪肉的亮度L和红度a缓慢下降.在Arrhenius动力学方程基础之上,建立了菌落总数、挥发性盐机氮和色差(亮度L和红度a值)与贮藏时间及贮藏温度之间的动力学模型.通过实验得到了各项指标变化预测模型中的EA及%Ko分别为:71.26kJ/mol,68.86kJ/mol,66.32kJ/mol,53.25kJ/mol和5.711×108、5.179×104、2.727×104、8.001×104.     

高压静电场联合食盐腌制对鮰鱼冷藏品质的影响

目的 对比高压静电场（High voltage electrostatic field,HVEF）、食盐处理,以及食盐与HVEF联合处理对鮰鱼冷藏（4℃）品质的影响,以期为鮰鱼片保鲜提供新方法。方法 将鱼肉样品分别进行腌制处理（盐处理组）、HVEF处理（电处理组）和联合处理（盐+电处理组）,以未进行任何处理的鱼肉为对照组,研究不同处理方式对鮰鱼冷藏过程中菌落总数、pH值、白度、微观结构、剪切力、离心失水率、硫代巴比妥酸（Thiobarbituric acid,TBA）值及总挥发性盐基氮（Total volatile basic nitrogen,TVB-N）值的影响。结果 随着冷藏时间的延长,鮰鱼肉的菌落总数、离心失水率、TBA值、TVB-N值整体呈上升趋势。在贮藏第7天时对照组样品已腐败,其菌落总数达到7.3 lg(CFU/g),超过最高安全限度,最高安全限度为7 lg(CFU/g),而处理组样品的菌落总数均小于5.5 lg(CFU/g)。与贮藏第7天时的盐处理组相比,高压静电场处理组样品的剪切力、白度、TBA值、TVB-N值相对较高。在贮藏第7天时,联合处理组样品的菌落总数、离心失...     

不同贮藏温度对自热食品货架期的影响

目的研究不同贮藏温度对自热食品(咖喱鸡块菜肴包)感官品质、pH值、L*(亮度)、a*(红绿色值)、b*(黄蓝色值)、挥发性盐基氮(Total Volatile Basic Nitrogen,TVB-N)值、硫代巴比妥酸反应物(Thiobarbituric Acid-reactive Substance,TBARS)值的影响。方法分别在温度为40,50,60℃下贮藏样品,然后测量其各项理化指标。结果贮藏温度对于咖喱鸡块的多项指标存在显著影响。在同一天测定时,温度越高,咖喱鸡块的感官评分、L*越低,而TBARS值、TVB-N含量越高;3个温度下样品pH值都呈现出较为激烈的波动态势,但贮藏温度为40℃时,变动程度相对较缓;a*在贮藏温度为50℃时有更为剧烈的变化趋势,其次是60和40℃;温度对样品b*的变化并未起到较大的作用。通过一级动力学方程和阿伦尼乌斯方程构建了咖喱鸡块菜肴包的货架期预测模型。结论通过皮尔逊相关性分析选取TVB-N作为判断因子,利用此模型得到的咖喱鸡块菜肴包货架寿命预测值与实际值相对误差低于10%,说明模型准确率较高。     

精准冰温对鲜牛肉贮藏品质的影响

在-2.5℃的冰温和0℃、4℃三种温度条件下贮藏排酸后的鲜牛肉,定期测定牛肉出汁率、TPA指标、色泽、p H、挥发性盐基氮(TVB-N)、微生物菌落总数等品质指标,为鲜牛肉的精准冰温保鲜提供参考。结果表明:冰温库库温稳定,在4℃、0℃和-2.5℃条件下贮藏的牛肉,有效保鲜期分别为8 d、15 d和24 d。在-2.5℃条件下贮藏24 d时,鲜牛肉p H值为5.59,TVBN含量为15.39 mg/100 g,微生物菌落总数为2.2×106CFU/g,色泽鲜红,无腐败异味出现。与4℃和0℃相比,-2.5℃冰温能够有效保持牛肉的颜色,减少出汁率,减缓p H值和TVB-N含量增大,抑制微生物的生长繁殖,有效延长生鲜牛肉的贮藏保鲜时间。     

温度对自热食品理化指标影响及其货架期预测方法

目的以自热食品土豆牛肉菜肴包为研究对象,考察温度对其贮藏品质的影响,同时建立自热食品土豆牛肉菜肴包的货架期预测模型。方法利用加速货架期实验的方法,研究不同贮藏温度下(40,50,60℃)土豆牛肉菜肴包品质的变化,通过相关性分析选定货架期预测的代表性指标,基于理化指标变化运用化学动力学模型、Q10模型和BP神经网络模型建立自热食品的货架期预测模型,对其常温下货架期进行预测。结果在3种温度下,样品pH值基本呈现先下降再上升最后下降的趋势,且温度越高变化越剧烈;3种温度下,均有L*值先缓慢下降后急剧下降,a*值先是快速升高之后速率逐渐减慢,b*值则是相对较稳定的缓慢上升的趋势;脂质氧化和蛋白质水解的反应速率加快,致使丙二醛和挥发性盐基氮含量增加。相较于化学动力学模型和Q10模型,基于先验条件的BP神经网络模型最适用于该自热食品货架期预测,最终误差收敛于7.16×10^-5,用该模型预测25℃土豆牛肉菜肴包的货架期为430d。结论温度对土豆牛肉菜肴包各项品质指标均有显著影响,同时确立了货架期预测的最优模型为考虑先验条件的BP神经网络模型。     

冰温贮藏对鹰爪虾鲜度及蛋白质特性的影响

目的 为了研究冰温贮藏对鹰爪虾的保鲜效果及品质的变化情况,以期为海捕虾的贮藏保鲜提供理论参考依据。方法 以鹰爪虾为研究对象,对预冷后在冰温和冷藏条件下贮藏后其pH值、新鲜度（K值）、挥发性盐基氮（TVB-N）值、菌落总数（TVC）、质构及蛋白质特性变化（如巯基含量、肌动球蛋白含量和钙激活三磷酸腺苷（Ca2+-ATPase）酶活性）等情况进行分析。对于冰温组的虾样,每间隔2 d测定其各项指标;对于冷藏组的虾样,每隔1 d测定其各项指标。结果 与冷藏组相比较发现,鹰爪虾在冰温贮藏过程中能够延缓pH值、TVB-N值、K值升高,抑制微生物的生长、TVC值的升高,延缓肌动球蛋白含量、巯基含量的降低,抑制Ca2+-ATPase酶的失活,能有效地延长鹰爪虾的贮藏货架期。结论 鹰爪虾在冷藏和冰温贮藏下的货架期分别为5 d和10 d,货架期延长了约5 d,因此冰温贮藏更易于海捕虾的贮藏。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Effect of Oxide Assisted Metal Nanoparticles on Microstructure and Morphology of Gallium oxide Nanowires

Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD.     

The Influence of Nitrogen and Boron Implant into Silicon Substrate on the Phase and Internal Stress of c-BN Films

Cubic boron nitride(c-BN) film was deposited on a Si (100) substrate by the RF-magnetron sputtering.The mainly problems for fabrication of c-BN films are the low purity and high intrinsic compressive stress. In order to solve the two problems, the c-BN film with the buffer interlayer was deposited on the substrate which had been implanted with nitrogen and/or boron ions. The results show: the implantation of nitrogen ions can obviously increase c-BN content and reduce the internal stress slightly; while the implantation of boron shows no obvious improvement to the content of c-BN, which can reduce the internal stress in the film obviously. In addition, it is suggested that the implantation of nitrogen and boron shows the best result, which not only can increase the content of c-BN, but also reduce the internal stress in the c-BN film obviously.