减震隔声降噪地垫的研发

介绍我国分户楼板隔声及其隔声研究现状,详细阐述多层复合结构的减震隔声降噪地垫的结构、性能和安装,减震隔声降噪地垫与木地板配合使用,将其铺装于扫平层的140 mm厚现浇钢筋混凝土楼板之上,经江苏省建工建材检测中心检测,撞击声隔声为61 dB,能很好地满足住宅分户楼板撞击声隔声L'nT,W≤65 dB的要求。     

双向渐厚综放工作面不同开采时期来压特征研究

针对焦作矿区首个综放工作面——九里山矿15081工作面的复杂开采技术条件,对其初采时期、局部放煤时期、放煤时期三个时期的基本顶来压步距与来压强度进行研究。根据理论计算和现场监测,揭示了该工作面在不同时期的来压特征:随着放煤范围的扩大,整个工作面的来压强烈程度会逐渐降低,直至基本消失;局部放煤时期与放煤时期相比,周期来压步距差距不大,来压强度较日常支架工作阻力水平略高。研究结果为矿井的安全高效绿色生产提供了理论指导与现场经验。     

Taking on a wider view: public value interests of construction clients in a changing construction industry

For financial and strategic reasons, public and semi-public construction clients increasingly depend on private parties to carry out public service delivery. They subcontract operational responsibilities to private parties while remaining socio-politically responsible for ensuring public values. Public administration literature mainly addresses the importance of procedural and performance values in safeguarding public values. However, safeguarding the quality of the built environment also requires a focus on product values. In this study, we aim to increase the understanding of the meaning and significance of public values in the daily practice of public construction clients and identify the challenges they face in commissioning these seemingly opposing values. A set of semi-structured interviews with the public administrators of a variety of public and semi-public construction client organizations in the Netherlands shows that both internal and external factors influence the collaborative practices between clients and contractors. This causes a value shift from an emphasis on procedural values to managing performance and product values, indicating that clients need to take on a wider view on public values. Six main public value dilemmas were found that complicate the task of developing an open, transparent and sustainable long-term client–contractor relationship. The current contractual system, however, lacks the flexibility to facilitate this product-based value view in construction.     

Study on the influence of three-grid assembly thermal deformation on breakdown times and an ion extraction process

In order to study the influence of three-grid assembly thermal deformation caused by heat accumulation on breakdown times and an ion extraction process,a hot gap test and a breakdown time test are carried out to obtain thermal deformation of the grids when the thruster is in 5 k W operation mode.Meanwhile,the fluid simulation method and particle-in-cell-Monte Carlo collision(PICMCC) method are adopted to simulate the ion extraction process according to the previous test results.The numerical calculation results are verified by the ion thruster performance test.The results show that after about 1.2 h operation,the hot gap between the screen grid and the accelerator grid reduce to 0.25–0.3 mm,while the hot gap between the accelerator grid and the decelerator grid increase from 1 mm to about 1.4 mm when the grids reach thermal equilibrium,and the hot gap is almost unchanged.In addition,the breakdown times experiment shows that 0.26 mm is the minimal safe hot gap for the grid assembly as the breakdown times improves significantly when the gap is smaller than this value.Fluid simulation results show that the plasma density of the screen grid is in the range 6?×10~(17)–6?×?10~(18) m~(13) and displays a parabolic characteristic,while the electron temperature gradually increases along the axial direction.The PIC-MCC results show that the current falling of an ion beam through a single aperture is significant.Meanwhile,the intercepted current of the accelerator grid and the decelerator grid both increase with the change in the hot gap.The ion beam current has optimal perveance status without thermal deformation,and the intercepted current of the accelerator grid and the decelerator grid are 3.65 m A and 6.26 m A,respectively.Furthermore,under the effect of thermal deformation,the ion beam current has over-perveance status,and the intercepted current of the accelerator grid and the decelerator grid are 10.46 m A and 18.24 m A,respectively.Performance test results indicate that the breakdown times increase obviously.The intercepted current of the accelerator grid and the decelerator grid increases to 13 m A and 16.5 m A,respectively,due to the change in the hot gap after 1.5 h operation.The numerical calculation results are well consistent with performance test results,and the error comes mainly from the test uncertainty of the hot gap.     

Effects of problem characteristics on the online helping behavior of shy individuals

The present research examined how problem characteristics might influence the online helping behavior of shy individuals. Three hundred undergraduates were recruited and assessed using the College Students’ Shyness Scale. According to the scores, 68 high-shy students and 68 low-shy students were selected to participate in simulated experiments designed to determine the influence of the shyness level, the presence of a foreseeable reward, the complexity of the problem, and the urgency of the problem influence online helping behavior. The results showed that (a) High-shy individuals tended to exhibit online helping behavior more for low-complexity problems and high-urgency problems than for high-complexity problems and low-urgency problems. (b) Low-shy individuals always exhibited online helping behavior less for high-complexity problems and when no reward was offered than they did for low-complexity problems and when a reward was offered. (c) High-shy individuals showed online helping behavior more than low-shy individuals did for no-reward, high-complexity problems and high-urgency problems. (d) Participants online had higher shyness scores for showing helping behavior than those offline.     

模糊综合评判在西南矿区沿空留巷适应性评价中的应用

沿空留巷技术在实际应用中表现出很大的优越性,为了使该技术在中小型煤矿中得到推广,综合运用层次分析法、模糊综合评判法建立了沿空留巷适应性评价模型。根据专家现场经验和试验研究结果,确定了影响适应性等级的6个主要地质因素,分别为煤层倾角、煤层厚度、巷道埋深、直接顶厚度影响系数、直接顶岩性和顶板完整性。采用层次分析法,通过构造判断矩阵,确定各个因素的权重。以西南某煤矿回采巷道为例,确定其留巷适应性等级为Ⅴ级,与实际留巷条件基本一致,表明该模型是合理可行的,能够实现对沿空留巷适应性等级进行评价。     

烃分压对乙烯裂解炉产物收率的影响

降低原料裂解时的烃分压有利于提高烯烃收率,而COP与稀释比是影响烃分压的重要参数。利用SPYRO软件模拟了COP和稀释比的变化对于裂解产物收率的影响。结果表明,采取较低的COP和较高的稀释比有利于提高乙烯裂解炉高附加值产物收率。     

Improving the service properties of metal structures working in the conditions of low climatic temperatures by methods of adaptive pulsed-arc welding

Experimental results confirm that the application of adaptive pulsed-arc welding with regulated heat input to welded material refines the structure of the metal, lowers the degree of softening of the fusion zone of the welded joint and greatly increases the mechanical properties of the welded joints, including structures working at low temperatures.     

WCDMA无线资源利用率分析

WCDMA网络承载语音和数据业务,通过无线资源利用率反映无线侧网络资源的有效利用情况。文中分析了与无线资源利用率相关的各种因素,提出有效提升网络无线资源利用率的手段,实现了用户感知和企业效益最大化的目标。     

A new version of Kovarik’s approximate orthogonalization algorithm without matrix inversion

In 1970 Kovarik proposed approximate orthogonalization algorithms. One of them (algorithm B) has quadratic convergence but requires at each iteration the inversion of a matrix of similar dimension to the initial one. An attempt to overcome this difficulty was made by replacing the inverse with a finite Neumann series expansion involving the original matrix and its adjoint. Unfortunately, this new algorithm loses the quadratic convergence and requires a large number of terms in the Neumann series which results in a dramatic increase in the computational effort per iteration. In this paper we propose a much simpler algorithm which, by using only the first two terms in a different series expansion, gives us the desired result with linear convergence. Systematic numerical experiments for collocation and Toeplitz matrices are also described.