Numerical Simulation and Experimental Research on Wake Field of Ships Under off-Design Conditions

Different operating conditions （e.g. design and off-design） may lead to a significant difference in the hydrodynamics performance of a ship, especially in the total resistance and wake field of ships. This work investigated the hydrodynamic performance of the well-known KRISO 3600 TEU Container Ship （KCS） under three different operating conditions by means of Particle Image Velocimetry （P/V） and Computational Fluid Dynamics （CFD）. The comparison results show that the use of PIV to measure a ship＇s nominal wake field is an important method which has the advantages of being contactless and highly accurate. Acceptable agreements between the results obtained by the two different methods are achieved. Results indicate that the total resistances of the KCS model under two off-design conditions are 23.88% and 13.92% larger than that under the designed condition, respectively.

Experimental Study on Hydrodynamics of L-type Podded Propulsor in Straight-ahead Motion and Off-Design Conditions

Experimental tests were conducted to evaluate the hydrodynamic performance of an L-type podded propulsor in straight-ahead motion and off-design conditions using an open-water measuring instrument developed by the authors for podded propulsors, a ship model towing tank, and under water particle image velocimetry （PIV） measurement systems. Under the three types of conditions, the main parameters of an L-type podded propulsor were measured, including the propeller thrust and torque, as well as the thrust, side force, and moment of the whole pod unit.In addition, the flow field on the section between the propeller and the strut was analyzed. Experimental results demonstrate that the dynamic azimuthing rate and direction and the turning direction affect the forces on the propeller and the whole pod unit. Forces are asymmetrically distributed between the left and right azimuthing directions because of the effect of propeller rotation. The findings of this study provide a foundation for further research on L-type podded propulsors.

Optimization of Culture Conditions and Medium Composition for the Marine Algicidal Bacterium Alteromonas sp. DH46 by Uniform Design

Harmful algal blooms(HABs) have led to extensive ecological and environmental issues and huge economic losses.Various HAB control techniques have been developed,and biological methods have been paid more attention.Algicidal bacteria is a general designation for bacteria which inhibit algal growth in a direct or indirect manner,and kill or damage the algal cells.A metabolite which is strongly toxic to the dinoflagellate Alexandrium tamarense was produced by strain DH46 of the alga-lysing bacterium Alteromonas sp.The culture conditions were optimized using a single-factor test method.Factors including carbon source,nitrogen source,temperature,initial pH value,rotational speed and salinity were studied.The results showed that the cultivation of the bacteria at 28℃ and 180 r min-1with initial pH 7 and 30 salt contcentration favored both the cell growth and the lysing effect of strain DH46.The optimal medium composition for strain DH46 was determined by means of uniform design experimentation,and the most important components influencing the cell density were tryptone,yeast extract,soluble starch,NaNO3 and MgSO4.When the following culture medium was used(tryptone 14.0g,yeast extract 1.63g,soluble starch 5.0 g,NaNO3 1.6 g,MgSO4 2.3 g in 1L),the largest bacterial dry weight(7.36 g L-1) was obtained,which was an enhancement of 107% compared to the initial medium;and the algal lysis rate was as high as 98.4% which increased nearly 10% after optimization.

Physiological Analysis for Universal Design of Public Seat Under Diverse Conditions

Public vehicle seats are used under diverse conditions, therefore, the design of these seats is desired to be universal design. In the past study, seat swing function used in public vehicle seats, and it was optimized from the mechanical aspect under diverse conditions. Seat swing function is the function to prevent hip-sliding force, which causes sitting uncomfortable feeling. Recent study clarified that the reduction of blood flow in the legs causes physiological dysfunction, which is one of the causes of Long Flight Thrombosis, and the social issue. Thus, in the design of seat swing function, it is necessary to consider not only mechanical aspects but also physiological aspects. For the universal design of seat swing function considering the physiological aspect （blood flow）, the influence of blood flow on seat swing function in diverse conditions was analyzed. The method of this study was measuring blood flow and body pressure distribution on seat cushion of seat swing function under diverse conditions. From the analysis, it was indicated that it was necessary to reduce the compressive force behind the knees of the user conditions; the short physique and the high weight physique in standard sitting posture, for the universal design of seat swing function to prevent reduction of blood flow in the legs.

Optimization of the Conditions for Using Sewage to Cultivate Navicula tenera

[ Objective] This study was to improve the biomass of Navicula tenera, and thus to provide reference for achieving the industrial production of Navicula tenera. [Method] The feasibility of using sewage to cultivate Navicula tenera was preliminarily investigated based on the consideration of regional characteristics; and a series of culture conditions including the nutrient source of nitrogen（N）, phosphorus（P）, iron（Fe）, silicon（ Si ） and the salinity in medium for culturing Navicula tenera, were optimized by single factor test and orthogonal design.[Result] The optimized conditions for cultivating Navicula tenera using sewage are as follows： the water from Xiaoerlou Artificial Lake of Nanjing University of Technology as basic solvent; 360 mg/L urea; 150 mg/L N2HPO4 · 12H2O; 50 mg/L ferric citrate; 2 000 mg/L Na2SiO3 · 9H2O; 2.0 mol/L salinity. Navicula tenera was strongly adaptive to sewage and could well uptake the nutrient sources in the sewage. Under the optimized conditions, the culture cost decreased, and meanwhile the biomass of Navicula tenera reached 4. 766 g/L which is 3.57 multiples over original medium and 1.9 multiples over optimized medium No. 1.[ Conclusion] This study laid a foundation for the combination of culturing Navicula tenera in large scale and sewage treatment.

Optimum conditions to treat high-concentration microparticle slime water with bioflocculants

We studied how bioflocculants,produced by white-rot fungi,affect flocculation in slime water.Based on a test in an orthogonal design,flocculation conditions were optimized.The results show that flocculation activity is at its highest when the following conditions are met:slime water concentration 27.42 g/L;coagulant aid(CaCl_2) mass concentration 5.0 g/L;two-segment stirrings:the first at a stirring speed of 60 r/min for 180 s and the second 180 r/min for 60 s;a pH of 11 and a flocculant concentration of 15 mL/L.The flocculation activity can be up to 98.71%of bioflocculants at the time.Further experiments indicate that most of the flocculation active material is found outside the mycelium cells.This is the extracellular secretion produced by mycelium cells during the fermentation process.This flocculant has strong thermal stability.Many kinds of cations have a flocculation function to assist bioflocculants.This aid-flocculation effect of the divalent cation Ca^(2+) is obvious in the bioflocculant produced by the white-rot fungus.Therefore,this is of great value when applied to control engineering in the battle against water pollution.

Optimization of Expression Conditions for Immunodominant Membrane Protein Gene of Phytoplasmas in E.coli

[Objective] This study aimed to increase the expression level of immun- odominant membrane protein gene （Imp） of phytoplasmas in E. coil BL21 （DE3）. [Method] On the basis of orthogonal experiment, effects of different culture conditions on recombinant bacteria E. coil BL21-pET-28a（＋）-Imp were investigated. Based on the obtained optimal culture condition, effects of different induction conditions on the ex- pression level of Imp protein were explored. The expression level of Imp fusion pro- tein was analyzed by using SDS-PAGE and Gene Tools software. [Result] The re- sults showed that the optimal conditions for culture were at 37℃, pH 7.0, with liq- uid volume of 20% and oscillation speed of 200 r/min, for induction were at 37℃ for 6 h, with initial OD600 of about 1.5 and IPTG final concentration of 0.1 mmol/L. [Conclusion] The expression level of Imp achieved 70.98 mg/L under the optimal conditions. Optimized conditions for expression of Imp fusion protein in E. coil were determined.

Enhanced production of elastase by Bacillus licheniformis ZJUEL31410:optimization of cultivation conditions using response surface methodology

Sequential methodology based on the application of three types of experimental designs was used to optimize the fermentation conditions for elastase production from mutant strain ZJUEL31410 of Bacillus licheniformis in shaking flask cul- tures. The optimal cultivation conditions stimulating the maximal elastase production consist of 220 r/min shaking speed, 25 h fermentation time, 5% (v/v) inoculums volume, 25 ml medium volume in 250 ml Erlenmeyer flask and 18 h seed age. Under the optimized conditions, the predicted maximal elastase activity was 495 U/ml. The application of response surface methodology resulted in a significant enhancement in elastase production. The effects of other factors such as elastin and the growth factor (corn steep flour) on elastase production and cell growth were also investigated in the current study. The elastin had no significant effect on enzyme-improved production. It is still not clear whether the elastin plays a role as a nitrogen source or not. Corn steep flour was verified to be the best and required factor for elastase production and cell growth by Bacillus licheniformis ZJUEL31410.

Hydrodynamic Efficiency Improvement of the High Skew Propeller for the Underwater Vehicle Under Surface and Submerged Conditions

An algorithm based on the Boundary Element Method(BEM)is presented for designing the High Skew Propeller(HSP)used in an Underwater Vehicle(UV).Since UVs operate under two different kinds of working conditions(i.e.surface and submerged conditions),the design of such a propeller is an unwieldy task.This is mainly due to the fact that the resistance forces as well as the vessel efficiency under these conditions are significantly different.Therefore,some factors are necessary for the design of the opti-mum propeller to utilize the power under the mentioned conditions.The design objectives of the optimum propeller are to obtain the highest possible thrust and efficiency with the minimum torque.For the current UV,the main dimensions of the propeller are pre-dicted based on the given required thrust and the defined operating conditions.These dimensions(number of blades,pitch,diameter,expanded area ratio,thickness and camber)are determined through iterative procedure.Because the propeller operates at the stern of the UV where the inflow velocity to the propeller is non-uniform,a 5-blade HSP is preferred for running the UV.Finally,the propel-ler is designed based on the numerical calculations to acquire the improved hydrodynamic efficiency.

Wall Conditioning Operation on the HL-2A Tokamak and Conceptual Design for the Device Modification

During the 2006 experiment campaign of HL-2A, about 2000 shots have been implemented, the plasma current of 433 kA and 3.0 s duration have been obtained. The wall conditioning methods such as glow discharge cleating （GDC） , siliconization and Ti sublimation were applied. The experiment results of wall conditioning research will be introduced in this report. At the same time, the conceptual design of modification of HL-2A tokamak has obtained great progress, two modification schemes have been obtained, and the conceptual design results will be presented.

Visual Interactive Computer Package for Air Conditioning System Design: Case of the International Conference Centre, University of Ibadan, Nigeria

Air conditioning design has become an interesting aspect of human life with the aim of seeking environmental comfort for indoor spaces. Analytical work involves in the design of air-conditioning system is often time consuming and laborious. This work therefore aims at developing a visual interactive computer package for the design of air conditioning system using the international conference centre, University of Ibadan, Nigeria as a case study. Procedures for calculating heat gain through various building components were discussed in detail. Cooling load analysis was carried out using standard cooling load equations obtained from the American Society of Heating, Refrigeration and Air conditioning Engineers (ASHRAE) handbook. A computer program was developed using java programming language to compute the total cooling load in the building. The result from the computer program was obtained within a very short period of time when compared with that of the manual one. The cooling load of the building obtained was 3,194,414 btu/hr;a visual interactive computer package for the design of air conditioning system has been developed and tested positively;hence can be used to design air conditioning system for any building.

Selection of Weather Parameters for Air-Conditioning System Design for Buildings with Long Thermal Lag

Two building factors-a longer thermal lag of more than one hour for building envelops and a lag of indoor radiation to convert into cooling load-have impact on the instantaneous heat input and instantaneous cooling load.So the two factors should be taken into account when selecting the weather parameters for air-conditioning system design.This paper developed a new statistic method for the rational selection of coincident solar irradiance,dry-bulb and wet-bulb temperatures.The method was applied to historic weather records of 25 years in Hong Kong to generate coincident design weather data.And the results show that traditional design solar irradiance,dry-bulb and wet-bulb temperatures may be significantly overestimated in many conditions,and the design weather data for the three different constructions is not kept constant.

FIDIC new conditions of contract and their applying prospects for the construction industry in China

In this paper, the author gives a brief introduction to the evolution of FIDIC conditions of contract, particularly the background of the 1999 new editions. A detailed discussion is made of the applying prospects referring to the new editions of FIDIC Conditions of Contract in China in 6 aspects: revisions of the existing model contract forms; finding solutions to the payment delay problem; advocating the Design/Build and EPC turnkey project delivery system; clarifying the roles of supervising engineers and opening up the new regions of their work. This paper also prepares a short form model contract for small projects in China, improving the settlement of construction disputes.

Surrounding rock deformation regularity of roadway under extremely complicated geological conditions in deep mine and its control

By combining the practices of deep mine mining in Changguang Mine field and using the Universal Distinct Element Code 3 0(UDEC3 0) numerical computing method, the distribution characteristics of deformation field and stress field as well as the surrounding rock deformation regularity of soft rock roadway are analyzed under extremely complicated geological conditions, a technical principle of bolting to control the surrounding rock of roadway is put forward. And also using a dynamic control for surrounding rocks designing method, the supporting parameters and implement plan are rationally determined. The experimental tests have obtained a good controlling result of surrounding rock.

BPSCCO Superconducting Films Grown by Spray Pyrolysis Technique: Systematic Study of the Relationship between Pb Content and Annealing Conditions

Actually recent investigation in developing semiconducting-superconducting composites based in CdS and Bi-based superconductors has attracted interest in processing thin superconducting films. In this work are reported Bi-Pb-Sr-Ca-Cu-O (BPSCCO) thin films grown on MgO substrates by spray pyrolysis technique from a solution containing Bi(NO3)3, Pb(NO3)2, Sr(NO3)2, Ca(NO3)2 and Cu(NO3)2, with a subsequent solid state reaction for growing the Bi-based superconducting phases. Annealed films were characterized by X-ray diffraction, atomic absorption spectroscopy and resistance measurements. Interdependence between Pb content, annealing time and temperature, in the formation of superconducting phases was studied applying a fractional factorial design 3III4-2. Interrelation between Pb content, ta and Ta exists. The presence of Pb is necessary to stabilize the high-Tc phase but its content depends on the annealing conditions.

Customized High-speed EMU Design Practice for Jakarta-Bandung HSR

The high-speed EMUs for Jakarta-Bandung high-speed railway(HSR)represent an important image and symbol of the Jakarta-Bandung HSR Project.By relying on the technical platform of the model CR400 EMU,the EMU is upgraded for the customized design in terms of adaptability to geographical environment and track conditions,integration of Indonesian cultural characteristics,etc.In the course of development,in order to accurately grasp the boundary conditions and solve matching adaptation problems,studies are conducted on the exploration of design boundary and the related special technology.With the systematic analysis and design experience summary of the high-speed EMUs for Jakarta-Bandung HSR,the paper aims to provide reference for the O&M of high-speed EMUs for Jakarta-Bandung HSR and the other similar overseas HSR projects.

Spectral transfer-learning-based metasurface design assisted by complex-valued deep neural network

Recently,deep learning has been used to establish the nonlinear and nonintuitive mapping between physical structures and electromagnetic responses of meta-atoms for higher computational efficiency.However,to obtain sufficiently accurate predictions,the conventional deep-learning-based method consumes excessive time to collect the data set,thus hindering its wide application in this interdisciplinary field.We introduce a spectral transfer-learning-based metasurface design method to achieve excellent performance on a small data set with only 1000 samples in the target waveband by utilizing open-source data from another spectral range.We demonstrate three transfer strategies and experimentally quantify their performance,among which the“frozen-none”robustly improves the prediction accuracy by∼26%compared to direct learning.We propose to use a complex-valued deep neural network during the training process to further improve the spectral predicting precision by∼30%compared to its real-valued counterparts.We design several typical teraherz metadevices by employing a hybrid inverse model consolidating this trained target network and a global optimization algorithm.The simulated results successfully validate the capability of our approach.Our work provides a universal methodology for efficient and accurate metasurface design in arbitrary wavebands,which will pave the way toward the automated and mass production of metasurfaces.

冷链物流技术在车辆工程专业教学中融合渗透研究——以A大学为例

文章从农业院校工科人才培养出发,开展冷链物流技术与车辆工程专业教学融合渗透研究,拟提高科学研究对本科教学的支持,在兼顾专业培养目标的前提下培养乡村振兴相关人才。以《汽车构造》中汽车空调相关教学内容为例,分析了当前汽车空调课程教学现状,提出传热学、计算流体动力学方法等内容的融合思路。最后,通过“三位一体”教学设计,提升教学内容与科学研究的结合度,促进学生对课程内容的理解。研究结果将对农业院校人才培养及车辆工程教学改革起到一定作用。

基于Plackett-Burman设计和响应面法优化枣花蜂蜜挥发性成分的萃取条件

为了提高蜂蜜中挥发性成分的顶空固相微萃取(head space-solid phase micro extraction,HS-SPME)效率,以便利用气相色谱-质谱联用仪(gas chromatograph-mass spectrometer,GC-MS)对其进行更精确的定性与定量分析,以枣花(Ziziphus jujuba Mill.)蜂蜜挥发性成分的色谱图总峰面积作为考察指标,采用Plackett-Burman(PB)设计和响应面(response surface methodology,RSM)对枣花蜂蜜的萃取条件(萃取温度、萃取时间、样品量、去离子水添加量、氯化钠添加量和搅拌速度)进行优化。结果发现,萃取温度、萃取时间和样品量对色谱图总峰面积影响显著。优化后的萃取条件为萃取温度68.5℃、萃取时间51.6 min、取样量5.1 g,在最优萃取条件下,色谱图总峰面积可达2.20×10^(9) mAU·min^(-1)。以上研究结果为蜂蜜中挥发性成分的进一步定性与定量分析提供一定的方法性指导。

基于Design-Expert软件设计优化大蒜多糖提取工艺

主要研究大蒜多糖提取的4种影响因素及其交互作用对大蒜多糖提取率的影响,借助于Design-Expert软件设计,优化大蒜多糖提取工艺条件,以期为开发利用大蒜多糖提供参考。采用水煮醇沉法提取大蒜多糖,以苯酚-硫酸法检测其含量,分别考察浸提时间、料液比、浸提温度及浸提次数对大蒜多糖得率的影响。在单因素试验的基础上,利用Design-Expert软件进行四因素三水平Box-Behnken试验设计,建立了大蒜多糖提取率和各因素之间的数学模型。结果表明,提取温度、液料比、提取时间和提取次数的一次项,个别交互项及其二次项对大蒜多糖得率的影响显著,而液料比与提取时间,液料比与提取次数的交互项作用不明显。大蒜多糖提取最优条件最终确定为:提取温度81℃,液料比14∶1(m L/g),提取时间84 min,提取次数2次。