The creation of the incapable social tenant in Flanders,Belgium. An appraisal

As long as the social rented sector housed traditional families and the allocation procedures were rather loose, there was little commotion about the sector. A combination of a change in family structures, economic changes, and the strengthening of allocation procedures in favour of those most in need did change perceptions. Marginalisation and ghettoisation, especially of high-rise social housing estates, became buzzwords. This paper deals with the causes of these changes and with their implications. The marginalisation discourse calls for enlarging the target groups and estate-specific allocation procedures (to obtain a `social mix'). It illustrates a profound desire to diminish the number of ethnic minorities, single parents, single-person households and all kinds of people with a weak income profile who gain access to social rental housing. Furthermore, this discourse is reaching a crescendo: after it was started in the early 1990s by staff members of local social housing companies, it passed through the union of the social housing companies, the umbrella organisation of the sector, and parliament, reaching its greatest momentum so far in early 2002 when it was adopted by the Flemish housing minister. The counterpoint to this negative discourse is the high degree of satisfaction among social tenants, as observed in a study carried out in 1999. In our paper we will try to explain the background of these opposing trends and the possible consequences for the social rental housing in general and for tenants in particular.     

C60泵送高性能混凝土在某工程中的应用

采用 5 2 5号普通硅酸盐水泥 ,掺加矿粉及高效减水剂 ,成功配制C60泵送高性能混凝土 ,工程应用效果良好。针对高性能混凝土高强度、高流动度、高密实度及体积稳定性等优点 ,详细分析了原材料的选择要求及配合比的设计要点 ,并对高性能混凝土的拌制、运输、浇注、振捣、养护、验收等施工工序分别提出了具体的方案要求。     

Effects of primary sludge particulate (PSP) entrapment on ultrasonic (20 kHz) disinfection of Escherichia coli

The role of primary sludge particulates (PSPs) in ultrasonic disinfection of Escherichia coli (E. coli) was investigated. Entrapment of E. coli by PSP was directly observed through scanning electron microscope (SEM) after E. coli and PSP were incubated together in water for 24 h at 35 °C. Entrapment coefficient was proposed for the first time to reflect the ability of PSP to entrap E. coli and was estimated as 1.4 × 10³ CFU/mg PSP under our experimental conditions. Ultrasonication (20 kHz) of different E. coli-PSPs solutions showed that the entrapped E. coli cells were protected by PSP from ultrasonication and the unentrapped cells were not. However, the protection of entrapped E. coli cells gradually decreased as ultrasonication proceeded, suggesting the ability of power ultrasonication to deprotect the entrapped E. coli cells. SEM studies suggested a two-step mechanism for ultrasonic (20 kHz) disinfection of entrapped E. coli: breakdown of the protective PSP refugia and disinfection of the exposed E. coli cells. This research will enable more informed decisions about disinfection of aqueous samples where porous PSP are present.     

桅杆结构动力特性研究

本文通过桅杆结构中纤绳和杆身动力特性的研究,建立了纤绳和杆身空间自由振动方程式,经过5层纤绳的桅杆实例计算,得到了相当满意的结果。     

Vibration Characteristic of Anchoring System of Bolt and Elastic Wave Propagation Law

Atpresent,theanchoringtechnologyiswidely usedinthefieldofmineraldiggingandrocksoilengi neering,anddevelopsquickly.Thereinforcement techniquesforboltcanreasonablystrengthenrock strengthandloadability,improvethestressstateof rock.Asaresult,itisappliedinthefieldofmining androcksoilengineeringonalargescale.Mean while,thereisanurgentneedforamethodtotest boltbondingquality.Atpresent,acommonlyused methodintheengineeringfieldispulloutexperiment andover coring,whichbelongstodestructivetestal thoughitha…     

石油醚对乳化炸药基质热分解动力学的影响

采用TG-DSC联用技术对混有石油醚的乳化基质样品的热分解动力学进行了研究,用Ozawa法和Satava-Sestak法对试验数据进行处理,得到各样品的动力学参数和机理函数.讨论了混入石油醚后乳化基质热分解动力学参数变化的原因,认为石油醚的加入会改变乳化基质的热分解动力学行为,具有促进乳化基质热分解的趋势.     

A segment probability method for calculating the molecular weight distributions of linear polycondensates in a continuous reactor

The molecular weight distribution (MWD) of polymers is a target of the optimization and control of industrial polymerization processes, as it dictates the processability and properties of polymers. A method, named as segment probability method, is developed to calculate the MWD of polycondensates produced by monomers of types A₂ and B₂ in a continuous reactor. It considers a growing chain as being composed of A and B segments in the middle of the chain and two terminal segments at the chain ends. It calculates the propagation probabilities of these different types of segments upon taking into account both the polycondensation and side reaction kinetics as well as the residence time distribution of the continuous reactor. The method is validated by poly(butylene terephthalate) (PBT) obtained from an industrial polymerization process composed of a continuous esterification reactor. The MWDs of the PBT calculated by this method are in agreement with those measured by size exclusion chromatography with mean square errors less than 10%.     

Assessment of hydraulic performance and fouling control caused by pulse flow in hollow fiber membrane module

To shed light on the effect of pulse flow on shear force and membrane fouling, the pulse frequency and flow velocity based on fiber Bragg grating (FBG) sensing technology were studied. The results show that there is a threshold for this synergy between the pulse frequency and flow velocity, which forms more easily at a high pulse frequency and low flow velocity. Moreover, the transition from pulse flow to continuous flow affects the shear force distribution with the membrane module height. Besides, at the same volumetric flow, Re gradually reaches a plateau as the pulse frequency increases from 1 to 5 Hz, and the membrane fouling control has a better flux recovery, which can reach a maximum of 28.89%. Finally, the results also show that the combined effect of high pulse frequency and low flow velocity would be higher than that of low pulse frequency and high flow velocity.     

Ternary fluid lattice Boltzmann simulation of dynamic interfacial tension induced by mixing inside microdroplets

A ternary fluid color-gradient lattice Boltzmann model is proposed to investigate the effect of mixing-induced dynamic interfacial tension on the diffusive mixing of two fluids inside microdroplets moving in a third continuous phase through a baffled channel. The diffusion coefficient of binary mixtures and dynamic interfacial tension in this model can be directly defined and independently adjusted. The simulation results show that the dynamic interfacial tension between miscible binary fluids at interfaces with ambient phase would lead to the motion of the interface and redistribution of solutes inside the droplet during mixing. The larger initial interfacial tension gradient would improve mixing efficiency at early stages by promoting faster solute flow. The present model can be easily applied to quantitatively characterize the mixing behavior inside droplets in the practical processes involving the dynamic interfacial tension phenomenon and inspire new designs for mixing intensification.     

气浮-ABR-生物接触氧化组合工艺处理豆制品废水

以200 t/d的豆制品废水处理工程为研究对象,采用气浮-ABR-生物接触氧化组合工艺对其进行处理。结果表明:当进水COD为8 409～14 501 mg/L、BOD₅为3 246～6 894 mg/L、NH₄⁺-N为41～111 mg/L、TN为187～365 mg/L、TP为21～39 mg/L时,组合工艺出水水质达到了当地污水处理厂纳管标准。该组合工艺对COD、BOD、TN、TP平均去除率分别达到98.31%、98.30%、91.23%和95.36%。该组合工艺具有工程费用低、运行费用少、耐冲击负荷能力强等优点。