PROPER CONDITIONS OF MESHING FOR Hy-Vo SILENT CHAIN AND SPROCKET

Proper meshing of Hy-Vo silent chain and sprocket is important for realizing the transmission of the silent chain with more efficiency and less noise. Based on the study of the meshing theory of the Hy-Vo silent chain with the sprocket and the roll cutting machining principle of the sprocket with the hob, the proper conditions of the meshing for the Hy-Vo silent chain and the sprocket are put forward with the variable pitch characteristic of the Hy-Vo silent chain taken into consideration, and the proper meshing design method on the condition that the value of the link tooth pressure angle is unequal to the value of the sprocket tooth pressure angle is studied. Experiments show that this new design method is feasible. In addition, the design of the pitch, the sprocket tooth pressure angle and the fillet radius of the sprocket addendum circle are studied. It is crucial for guiding the design of the hob which cuts the Hy-Vo silent chain sprocket.

MESHING THEORY AND DESIGN METHOD OF NEW SILENT CHAIN AND SPROCKET

Based on the study of the meshing theory of a new silent chain and sprockets, and the rolling cutting theory of sprocket and hob, the harmonious relations of dominating dimensions among the new silent chain, sprocket and hob is build, the meshing conditions are expatiated, and the resolved expression, which can instruct design and calculation, is educed. The tests show that the meshing design method is feasible.

Bayesian Markov chain Monte Carlo inversion for anisotropy of PP-and PS-wave in weakly anisotropic and heterogeneous media

A single set of vertically aligned cracks embedded in a purely isotropic background may be con- sidered as a long-wavelength effective transversely iso- tropy （HTI） medium with a horizontal symmetry axis. The crack-induced HTI anisotropy can be characterized by the weakly anisotropic parameters introduced by Thomsen. The seismic scattering theory can be utilized for the inversion for the anisotropic parameters in weakly aniso- tropic and heterogeneous HTI media. Based on the seismic scattering theory, we first derived the linearized PP- and PS-wave reflection coefficients in terms of P- and S-wave impedances, density as well as three anisotropic parameters in HTI media. Then, we proposed a novel Bayesian Mar- kov chain Monte Carlo inversion method of PP- and PS- wave for six elastic and anisotropic parameters directly. Tests on synthetic azimuthal seismic data contaminated by random errors demonstrated that this method appears more accurate, anti-noise and stable owing to the usage of the constrained PS-wave compared with the standards inver- sion scheme taking only the PP-wave into account.

Design,Synthesis and Crystal Structure of Two One-dimensional Zigzag Chain-like Compounds

Two one-dimensional chain-like cyanide-bridged compounds, [Fe（Phen）2（CN）2Ni（Cyclam）]（ClO4）2·DMF-2H2O 1 （Cyclam = 1,4,8,11-tetraaza-cyclotetradecane, Phen = 1,10-phenanthroline, and DMF = N,N-dimethylformamide） and [Fe（Phen）2（CN）2Zn（Cyclam）]（PF6）2·CH3CN 2, were prepared by the reaction of [Fe（Phen）2（CN）2]·2H2O with M（Cyclam）^2＋ （M = Ni, Zn）. In complexes 1 and 2, the metal atoms are connected alternatively with CN groups. X-ray structure and IR analyses for 1 and 2 were performed. Structure analysis revealed that both complexes are centrosymmetric and the geometry around each metal atom is an octahedron. The two complexes crystallize in triclinic with space group of P^1-. For 1, a = 10.439（4）, b = 14.976（7）, c = 15.914（8）A,α = 83.168（15）, β = 74.338（15）, γ = 78.023（15）°, V = 2338.3（18）A^3, Z = 2, Mr = 1035.37, Dc = 1.471 g/cm^3, F（000） = 1076,μ = 0.895 mm^-1, the final R = 0.0616 and wR = 0.1414 for 5849 observed reflections （1 〉 2σ（I））. For 2, a = 9.656（6）, b = 15.404（9）, c = 15.822（10）A, α = 78.68（2）, β= 78.917（19）, γ = 77.15（2）°, V = 2223（2）A^3, Z = 2, Mr = 1064.87, Dc = 1.587 g/cm^3, F（000） = 1078,μ = 1.032 mm^-1, the final R = 0.0672 and wR = 0.1595 for 6819 observed reflections （I 〉 2σ（I））.

Store Environment:Its Importance and Consumers'Expectations on Casual-wear Chain Stores in Honk Kong

This study attempted to examine the importance of storeenvironment in affecting consumers’store choice deci-sion;the relative importance among the three environ-mental factors;and consumers’expectations on store en-vironment for the casual-wear chain stores in HongKong.Julie Baker’s Three-category framework onstore environments namely ambient,design and socialfactors was adopted for investigation.The results indi-cated that the store environment was important in affect-ing consumers’selection of store for shopping.It alsorevealed that social factor was perceived relatively im-portant than ambient and design factors.Nine store ex-pectation dimensions were categorised and the resultdemonstrated that most respondents were concerned onthe social aspect in their expectation of having a satisfy-ing store environment.

Hydrogen-bonded Three-Dimensional Networks Encapsulating One-dimensional Covalent Chains: [Cu(3-ampy)(H_2O)_4](SO_4)·(H_2O) (3-ampy = 3-Aminopyridine)

A three-dimensional complex [Cu（3-ampy）（HEO）4]（SO4）·（H2O） （3-ampy = 3-amino- pyridine） has been synthesized. Crystallographic data： C5H16CuN2O9S, Mr = 343.80, triclinic, space group P1, a = 7.675（2）, b = 8.225（3）, c = 10.845（3）A, α= 86.996（4）, β = 76.292（4）, γ= 68.890（4）°, V = 620.0（3）A^3, Z = 2, Dc = 1.841 g/cm^3, F（000） = 354 and μ = 1.971 mm^-1. The structure was refined to R = 0.0269 and wR = 0.0659 for 1838 observed reflections （I 〉 2a（/））. The structure consists of [Cu（3-ampy）（H2O）4]^2＋ cations, SO4^2- anions and lattice water molecules. 3-Ampy acting as a bidentate bridging ligand generates a 1D covalent chain. A supramolecular 2D framework is formed through π-π stacking of pyridine rings. The lattice water molecules and SO4^2- anions are located between the adjacent 2D frameworks. The hydrogen bonding interactions from lattice water molecules and SO4^2- anions to coordinate water extend the 2D framework into a 3D network.

Synthesis and Crystal Structure of an Infinite 1D Zigzag Chain Compound (dimbH^+)(ClO_4^-) and Its Comparison with (dimb)2H_2O (dimb = 1,3-Di(imidazol-1-ylmethyl)-5-methylbenzene)

A new imidazolium compound, C15H17N4ClO4, was prepared from a flexible bidentate ligand of 1,3-di(imidazol-1-ylmethyl)-5-methylbenzene, and characterized by X-ray analysis. It is of orthorhombic, space group Pnma with a = 8.182(2), b = 12.874(3), c = 15.611(4) ? V = 1644.4(7) 3, Dc = 1.425 g/cm3, Z = 4, Mr = 352.78, m(MoKa) = 0.944 mm-1, F(000) = 736, S = 1.036, the final R = 0.0521 and wR = 0.1187 for 1128 observed reflections (I > 2s(I)). An infinite one-dimensional zigzag chain is formed by NH…N hydrogen bonding interactions between the imidazolium salt cations.

Novel Cascade Refrigeration Cycle for Cold Supply Chain of COVID-19 Vaccines at Ultra-Low Temperature -80°C Using Ethane (R170) Based Hydrocarbon Pair

Several media report highlight on that the pharmaceutical companies require ultra-low temperatures -80°C to transport and store its COVID-19 vaccines. This research presents the thermodynamic analysis on cascade refrigeration system (CRS) with several refrigerant pairs which are R32/R170, R123/R170, R134a/R170, R404A/R170, R407c/R170, R410/R170, and the hydrocarbon (HC) refrigerant pair Propane/Ethane, namely R290/R170. Besides, the results of R22/R170 pair, which is not recommended to be used due to phase out of R22 as per Montréal Protocol, are included as base case to compare the novel hydrocarbon pairs in CRS and the old trend of refrigerant pairs. Thermodynamic properties of all these pairs were investigated and compared under different intermediate temperature used in CRS heat exchanger, which thermally connected both the Low and High temperature cycles (LTC) and (HTC). By applying the first law of thermodynamics, the coefficients of performance (COPs) and the specific power consumptions (SPC) in kW/TR are presented and compared. In addition, by applying the second law of thermodynamics the exergetic efficiencies were estimated. The results reveal the promising opportunity of using the HC pair (R290/R170). The minimum SPC in kW/TR is recorded for the pair R123/R170. One the other hand, the highest exegetic efficiency values are observed to be 40%, 38%, and 35% for the pairs R123/R170, R290/R170, and R134/R170, respectively. This research concludes that the HC pair (R290/R170) is highly recommended for CRS applications either to transport the COVID-19 or store it in cold storage rooms in hospitals and clinics. All precautionary measures should be carefully applied in design and operation of HC pair (R290/R170) due to its flammability hazard.

Studies on polyoxymethylene dimethyl ethers production from dimethoxymethane and 1,3,5-trioxane over SO_(4)^(2-)/ZrO_(2)-TiO_(2)

Polyoxymethylene dimethyl ethers(OMEs)with physical properties similar to those of diesel has received significant attention as green additives for soot emission suppression.Herein,series of SO_(4)^(2-)/ZrO_(2)-TiO_(2)catalysts were developed for OMEs production from dimethoxymethane(DMM)and1,3,5-trioxane through sequential formaldehyde monomer insertion into C-O bond of DMM.Not Lewis but Bronsted acid sites were identified to be active for the decomposition of 1,3,5-trioxane into formaldehyde unit,however,both of them are effective for the chain propagation of DMM via formaldehyde unit insertion into C-O bond.Kinetic studies indicated each chain growth step exhibited the same parameters and activation barrier on corresponding Bronsted and Lewis acid sites due to the same reaction mechanism and very similar chemical structure of OMEs.Also,the catalytic stability investigation suggested the deactivation behavior was derived from the carbon deposition,and the decay factor could be exponentially correlated with the amount of coke accumulation.

基于心形孔的Hy-Vo齿形链的啮合分析及其设计方法

基于Hy-Vo齿形链与链轮刚柔传动的啮合原理及其链轮滚刀与链轮的滚切原理,以Hy-Vo齿形链工作链板齿形视作滚刀法向齿形的设计理念,建立基于心形孔的Hy-Vo齿形链—链轮—刀具齿条的啮合设计体系;根据Hy-Vo齿形链链轮与刀具齿条的共轭啮合条件,提出当工作链板齿形角不等于渐开线齿形链轮压力角时的参数变换的啮合设计方法,并进行实例设计计算。通过171 h台架磨损试验,研究该新型Hy-Vo齿形链的耐磨特性,由于该新型Hy-Vo齿形链链板孔形状类似心形,组成异型销轴截面的各段圆弧均为外凸曲线,因而异型销轴与链板心形孔外侧曲线定位时,比圆形基准孔和长腰形基准孔更稳定,接触面积更大,该新型Hy-Vo齿形链具有较高的耐磨性,试验研究表明,这种新的啮合设计体系和设计方法是科学的,是切实可行的。

4GZ-56型履带式甘蔗联合收获机设计与试验

在消化吸收国外甘蔗收获机械先进技术的基础上,设计了一种切段式甘蔗联合收获机。该机能够在甘蔗收获作业过程中一次完成分行、根部切割、输送、切段、风选杂质和收集蔗段等工序的作业。对各工序主要装置的设计进行了简述,并在甘蔗存在严重倒伏的田间对该样机的主要性能指标进行了测试,实测的各项指标为总损失率2.25%、宿根破头率11.3%、含杂率7.75%、蔗段合格率94.55%和切割高度合格率94.3%。结果表明,该机能够在倒伏严重的蔗田顺利作业,各项指标达到了设计要求。

基于多元变异的Hy-Vo齿形链设计方法

阐述了Hy-Vo齿形链的多元变异特性,构建了Hy-Vo齿形链-链轮-刀具齿条的啮合设计体系,提出了Hy-Vo齿形链与链轮正确啮合就位的必要条件,指出了在拉直状态下Hy-Vo齿形链节距和当量边心距的一致性是多元变异设计的重要基础条件,分析了缠绕圆和接触圆在啮合设计时的相互关系。实践研究表明,Hy-Vo齿形链的多元变异设计方法是实现产品创新升级和知识产权保护的重要手段,是科学而切实可行的。

新型Hy-Vo齿形链与链轮的啮合分析及其设计方法

在分析与计算新型Hy-Vo齿形链变节距特性的基础上,提出'当量边心距'的概念,指出'定位偏置角'的设计原则。在研究新型Hy-Vo齿形链、链轮、滚刀之间的啮合与滚切原理的基础上,建立三者之间主要参数的谐应关系,提出可用于指导新型Hy-Vo齿形链、链轮及其滚刀设计计算的解析表达式。试验研究表明,这种新的设计方法是切实可行的。

Hy-Vo齿形链与链轮的刚柔耦合接触动力学特性研究

基于多体动力学软件RecurDyn,建立了Hy-Vo齿形链与渐开线链轮的刚柔耦合接触动力学仿真模型,研究了Hy-Vo齿形链与链轮在啮合过程的动态接触应力,分析了对滚异形销轴之间的接触应力的变化规律,研究结果表明,刚柔耦合接触动力学分析技术为研究Hy-Vo齿形链与链轮传动过程中真实接触区域的力学特性提供了一种切实可行的研究方法。

Hy-Vo齿形链链轮公法线长度的计算方法

在分析Hy-Vo齿形链链节围在链轮轮齿上定位时其节距增量和当量边心距增量对链轮公法线长度影响的基础上,根据Hy-Vo齿形链与链轮的正确啮合条件,通过参数变化,建立了Hy-Vo齿形链—链轮—滚刀三者之间的啮合设计体系,提出了既适用于链板齿形角等于链轮压力角情况,也适用于链板齿形角不等于链轮压力角情况的Hy-Vo齿形链链轮公法线长度的计算方法。试验研究表明,这种新的计算方法是科学的,也是切实可行的。指出了大负变位、短齿、齿顶倒大圆角结构形式的Hy-Vo齿形链链轮公法线长度、跨测齿数的计算与修正方法。

链板-链条输送机的设计及推广应用

通过笔者设计的该输送机应用实例,阐明了链板输送机的设计方法、理论计算以及使用场合,解析了该机械的特性。使用实践证明该输送机具有结构合理、制造方便、标准化程度高、使用寿命长等特点,值得推广应用。

浅析长节距米制输送链条与链轮

非标设计的取料系统是顶堆侧取堆取料机中的重要组成部分。本文详细介绍了驱动链轮组链轮轮齿关键参数,并对链轮齿形优化设计方案进行了介绍,着重阐述非标设备中链条传动的运动特性,总结了链条工作中产生冲击力的原因及减少冲击力的措施,为确保非标设计顶堆侧取堆取料机符合技术要求和提升设备实际使用效果提供了借鉴和参考。

7 m大采高工作面巷道转载机改进设计与应用

针对神东7 m大采高工作面巷道转载机在使用中存在刮板弯曲断裂、链轮密封失效等问题,通过分析刮板和链轮组件的失效特征及零部件的受力状况,采取升级链条、增大刮板断面和链轮轴直径、优化链条中心距等措施,全面改善刮板和链轮组件受力状态,刮板强度提高1.7倍,轴承支撑部位链轮轴的挠度降为1/8,零部件性能显著提高。设备改造时充分考虑到零部件的通用性,机头架和槽体可以直接使用,降低了改造成本。通过对进口设备进行改造,积累了经验,推动国产煤机装备的发展。

折弯机链轮的修形研究及其影响

针对某折弯机链传动系统引起的冲击和疲劳破坏问题,对链传动的动态特性和链轮的修形进行了分析研究。从理论角度上分析了链传动的运行特点;利用RecurDyn软件建立了折弯机链传动系统的仿真模型,对其进行了动力学仿真分析和轮齿静强度分析;采用齿顶圆修形的方法,建立了短修形和长修形两种修形后的仿真模型,得到修形后从动链轮受力、啮合力、传动误差和链轮轮齿静强度的变化曲线图。研究结果表明,短修形有效降低了折弯机链传动过程中的啮合冲击力,链轮链条间啮合力峰值下降了43.64%,轮齿所受等效应力最大值降低了14.69%,有效提高了齿面强度,增加了链轮的使用寿命,相较于长修形更适用于折弯机链传动系统。