Mineralogical and chemical properties of FGD gypsum from Florina,Greece

BACKGROUND: The aim of this work is to define the chemical and mineralogical composition of the fuel gas desulphurization (FGD) gypsum produced from the Meliti thermal power plant in the region of Florina in North West Greece, in order to investigate potential uses in the cement industry. Mineralogical and microprobe analyses were carried out on FGD gypsum samples collected from the Meliti 330 MW lignite‐fired power plant. RESULTS: Results show that the main component of the FGD gypsum is pure mineral gypsum (CaSO₄·2H₂O). The particle size of the gypsum ranges from 5 to 50 µm and the crystals are mainly of rhomboid shape. Microprobe analysis shows that the concentration of CaO and SO₃, which are the main components, range from 31.9%–32.5% and from 45.90–46.40%, respectively. CONCLUSION: This FGD gypsum can easily substitute the natural gypsum used in the production of cement. Copyright © 2007 Society of Chemical Industry     

Performing integrated system tests using malicious component insertion

In this paper, a testing method suitable for strengthening fault tolerance in the event of unexpected situations within a software system is presented. It is based on the idea of testing an integrated system, by substituting system components with other, similar in design and functionality that operate in an erroneous and even malicious manner. The approach adopted, is similar to the concept of inserting a virus within an organization so that the defense mechanisms of the latter can be tested and the necessary lines of defense are formed, so that the virus cannot affect any of the organization critical parts. The focal point is to ensure that in case of a module malfunction, the integrated system will continue to operate, isolating the malfunctioning software at the greatest possible extend, preventing the erroneous behavior from affecting other (and sometimes critical) modules. The testing method proposed is based first on isolated components testing adopting and enhancing the Component Off The Self method, and second on integrated system testing using malicious components that emulate erroneous operation.     

On the design and fabrication by two-photon polymerization of a readily assembled micro-valve

This paper reports on the conceptual design and fabrication of a complex shape, readily assembled micro check valve using the two-photon polymerization technique. The material used for the fabrication of the valve is a zirconium containing organic–inorganic hybrid photosensitive sol-gel known to exhibit negligible distortion during photopolymerization. A preliminary computational fluid dynamics study has been carried out in order to evaluate the flow performance of the valve under blood pressures exhibited in healthy human veins. The fabricated micro-valves exhibit good dimensional accuracy when compared to the CAD-created valve design and the capability of an internal moving component to perform its intended function.     

Numerical studies on the effect of plan irregularities in the progressive collapse of steel structures

This research examines the effect of plan irregularities on the progressive collapse of four steel structures located in regions with different seismic activity. The plans of the first and second structure are irregular, whilst those of the third and fourth structures are regular. The collapse patterns of the four buildings are examined and compared under seven loading scenarios using non-linear dynamic and static analyses. In the non-linear dynamic analyses, node displacements above the removed columns and the additional force on the columns adjacent to them are discussed. Furthermore, the strength and capacities of the columns are compared to determine their susceptibility to collapse. In the non-linear static analyses, the pushdown curve and yield load factor of the structures are obtained after column removal. The results indicate that an irregular structure designed in site class C seismic zone, collapses in most of the column-removal scenarios. Moreover, when comparing regular and irregular structures designed in site class E seismic zone, the demand force to capacity ratio (D/C) of the columns in the irregular structures is on average between 1.5 and 2 times that of the regular ones.     

Interactions between bacterial isolates from modified-atmosphere-packaged artisan-type cooked ham in view of the development of a bioprotective culture

Growth and metabolite production of three dominant bacterial isolates (Carnobacterium divergens 3M14, Leuconostoc carnosum 3M42, and Brochothrix thermosphacta RMS6) from modified-atmosphere-packaged (MAP), artisan-type cooked ham were assessed for their interactions in view of the development of a bioprotective culture. During monoculture experiments in cooked ham simulation medium, Leuc. carnosum 3M42 converted the available glucose into lactic acid and ethanol, whereas the two other strains produced additional metabolites such as acetic acid and 3-methyl-1-butanol. When grown in co-culture, Leuc. carnosum 3M42 suppressed the growth and metabolism of B. thermosphacta RMS6. In contrast, a co-culture of the latter bacterium with C. divergens 3M14 led to a variety of spoilage-related metabolic compounds. Subsequently, experiments with a commercial cooked ham product indicated that Leuc. carnosum 3M42 dominated the meat matrix and improved acceptability of the product over time, hence acting as a bioprotective culture for MAP, artisan-type cooked ham.     

拱桥的平面内屈曲性能研究

对系杆拱桥进行有限元建模,分析拱的平面内屈曲长度系数,并将其与EC3中推荐的数值进行比较。首先简要介绍了EC3中针对拱的平面内屈曲性能提出的分析方法。随后说明了系杆拱桥的模型、桥梁特性和计算方法,并进行了参数分析。同时也对拉索损坏的情况进行了讨论。最后归纳了研究结论。     

A Small Area Charge Sensitive Readout Chain with a Dual Mode of Operation

A charge sensitive readout chain has been designed and fabricated in acommercially available 0.8 m CMOS technology. The readout chain is optimizedfor pixel detectors measuring soft X-ray energies up to 20 KeV. In the first modean analog signal proportional to input charge is generated and processed in realtime. In the second mode a peak-and-hold operation is enabled and therelevant signal is processed in later time. This dual mode of operation iscontrolled by an external digital signal. The readout chain consists of a chargeamplifier, a shaper, an operational amplifier which can either operate as avoltage amplifier or a peak detector and an output buffer. Its area is . The gain at the shaper output is 378 mv/fC, theENC is 16 rms at 160 nsec shaping time. The overall gainis 557 mV/fC, the ENC is rms with 240 nsec peaking timeand 1.4 sec recovery time. The overall power dissipation is 1.5 mWatt with aload capacitance of 25 pF.     

Automatic derivation of BPEL4WS from IDEF0 process models

Integration definition for function modelling (IDEF0) is one of the most popular notations for modelling business processes. It employs a rather simple and intuitive modelling construct, consisting of boxes representing functions and arrows connecting them signifying flow of information and materials. Web services on the other hand are an emerging technology for implementing distributed systems. Web service orchestration languages, such as Business Process Execution Language for Web Services (BPEL4WS), are the emerging approach for describing processes as networks of coordinated web services. Business processes as captured in IDEF0 models, however, may contain both web services as well as other types of activities which need to be coordinated. By automatically analysing the Extensible Markup Language (XML) definition of an IDEF0 model, we can identify how web services interact with other activities and at runtime generate code to support the orchestration of web services with the overall business process. The approach proposed is independent of the orchestration language and ensures an implementation independent model for specifying web service orchestrations. This approach also enables the top-down analysis of a business process to its constituent web services and avoids any misalignment problems during design time between the two.     

Linear micropolar elastic crack-tip fields under mixed mode loading conditions

Micropolar elasticity laws provide a possibility to describe constitutive properties of materials for which internal length scales may become important. They are characterized by the presence of couple stresses and nonsymmetric Cauchy stress tensor. Beyond the classical displacement field, the kinematical variables are augmented by a so-called microrotation field and its gradient, the latter introducing an internal length scale in the theory. For an isotropic, linear micropolar elastic material, the near-tip asymptotic field solutions for mode I and mode II cracks are derived. It is shown that these solutions behave similar to those according to the so-called couple stress theory, which has been investigated by Huang et al. (1997a), or similar to those derived for cellular materials by Chen et al. (1998). In particular, the singular fields have an order of singularity r ^–1/2 and are governed by some amplitude factors, having the meaning of stress intensity factors as in the classical linear elastic theory. The effect of material parameters on the stress intensity factors is studied by applying the finite element method to calculate the values of the stress intensity factors for an edge-cracked specimen of finite width.