A New Method for Siting Hazardous Units in Chemical Process Facilities Which Minimizes Risk at Least Cost: RIDIMPUS

A new method, RIsk and DIstance Minimization in Process Units Siting (RIDIMPUS), is presented with which hazardous units can be sited in a chemical process facility in a manner that the risk of accidents involving the hazardous units as also the cost of spacing the units is minimized. To achieve this, safety and cost factors were modeled using various governing parameters and then expressions were designed to integrate the safety and the economic concerns to form model equations, inequalities and disjunctions. The resulting nonlinear programming model is solvable by using algorithms and solvers on any common desktop computer, thereby providing an optimal and prompt solution.     

Failure Analysis of Fan Motor Shafts of a Tunnel Dryer

This article details the analysis of two conducting shafts operating on blowers of a tunnel dryer. A deductive analysis was applied looking toward a successful recognition of root cause(s), where based on knowledge of background, and failure characteristics, multiple hypothesis are exposed that are further confirmed or rejected according to different tests, material analysis or maintenance history. In both shafts, failure arises from inadequate repairing. In order to confirm this, the failure analysis methodology included the following steps: technical review, visual inspection, fractography, penetrating inks, metallography, optic microscopy and stress analysis. Evidence obtained through these techniques indicates a fatigue failure induced by inadequate repairing procedures; therefore, main recommendation is to take the necessary precautions in order to guarantee minimal alterations on shaft geometry or material microstructure.     

Screen printing for support-pillar placement for vacuum glazing and the effects of pillar spacing on strength properties

Maintaining a vacuum between the two glasses to maximize the heat insulating performance, it is indispensable to array the pillar for the vacuum glazing to maintain the vacuum gap. In this paper, to investigate the effect of the spacing of the pillars arranged using the screen printing method on the strength of the glass, a bending strength test was carried out by design and fabricating a ROR bending strength test jig based on the Euro standard. In the strength test results, the experimental results were analyzed using the Weibull distribution, which is a statistical analysis method mainly used for evaluating the breaking strength of brittle material. Based on the analysis results, the placement spacing of the pillars proved validity for maintaining the vacuum glass gaps.     

Designing a secure designated server identity-based encryption with keyword search scheme: still unsolved

There exist only a few papers in the literature which target the problem of “proposing a secure designated server identity-based encryption with keyword search scheme.” In this paper, we prove that they all suffer from security issues, and therefore, this challenging problem still remains open.     

Price competition between a macrocell and a small-cell service provider with limited resources and optimal bandwidth user subscription: a game-theoretical model

The ever-increasing demand for higher data rates in wireless commutations provides a rationale for small cells deployment. While the physical and technological aspects of small-cell networks have been extensively studied in recent years, the economic analysis has received much less attention. We focus on the economic rationale for a small-cell service provider (SSP) operating a market where an incumbent macrocell service provider (MSP) exists, and competition develops. We analyze such scenario for the case of fixed users by means of Game Theory, specifically through a two-stage game: in the first stage each service provider posts its price according to a Stackelberg game where the MSP is the leader and the SSP is the follower; and, in the second stage, each user chooses both which provider to subscribe to and the optimal amount of bandwidth. A subgame perfect Nash equilibrium is used as a solution concept, and it is derived analytically. We show that the SSP has an incentive to operate in the market and its profit gets higher as SSP’s resources increase. Furthermore, users benefit from SSP’s operation, which may provide a rationale for a regulatory authority to grant the SSP access to the market, despite the fact that MSP’s profit is harmed. Finally, we identify two modes of operation of the system, which depend on the SSP coverage: one where SSP’s deployment is limited and the MSP strategy is not affected by SSP competition and takes only the users outside the SSP coverage; and another, where the SSP covers a large area and the MSP competes against the SSP taking a fraction of the users inside the small cells.     

Bias voltage effect on the dielectric properties of organic–inorganic blend SiNWs elaborated via metal assisted chemical etching

The electrical proprieties of poly (3-hexylthiophene): Silicon nanowires (P3HT: SiNWs) nanocomposite was investigated by impedance spectroscopy technique. The effect of bias voltage under and without illumination was discussed. Indeed, the imaginary part of the impedance shows a high relaxation frequency related to Maxwell–Wagner–Sillars (MWS) polarization. The relaxation time was found in the range of ms and it was shifted towards high frequency with increasing the bias voltage especially at 0.6 V At bias voltage equal to V_th and under illumination, the conductivity increases because the trapped charges acquire the necessary energy to escape from the interface and the hopping time found was reduced. This indicates a change of the conduction mechanism. The Cole–Cole diagram was excellently fitted through an equivalent circuit including a chemical capacitance Cµ, a contact electrical resistance Rs and recombination resistance Rp.     

Photoelectrocatalytic Reduction of CO<Subscript>2</Subscript> to Chemicals via ZnO@Nickel Foam: Controlling C–C Coupling by Ligand or Morphology

The CO₂ reduction is a very attracting research field in the environmental, material and chemical sciences in light of the energy crisis and greenhouse effect. A new photoelectrocatalytic system composed of a photoanode BiVO₄ and a photocathode of nickel foam supported ZnO semiconductor was designed, assembled and applied to CO₂ reduction in water. The photocathodes with different morphology could be made from electrochemical deposition method and well characterized by SEM, UV–Vis, XRD, and XPS. The photoelectrocatalytic cell of ZnO/Ni-30|KHCO₃|BiVO₄ can produce ethanol and acetic acid in a rate of 12.5 µM h^?1 cm^?2 with 100% selectivity for C₂ product, attributing to the controlling of 3D-spaces of nanorod. The cell of A-ZnO/Ni-15|KHCO₃|BiVO₄ produces ethanol and acetic acid with 75% selectivity for C₂ product under 100 mW cm^?2 simulated sunlight irradiation, attributing to controlling of both amine ligand and morphology of ZnO, which reveal a new way to increase the selectivity of products.     

Preparation of proanthocyanidin–chitosan complex and its antioxidant and antibacterial properties

Chitosan (CS) is a natural polysaccharide with beneficial effects on human health. To further strengthen its biological properties, a CS-based complex was prepared by combining it with proanthocyanidin (PA) and named it as PA–CS in this study. The successful preparation of PA–CS was confirmed by Fourier transform infrared spectroscopy. The size of PA–CS particles was distributed between 10 and 100 µm with a mean value of 30.6 µm and low pH and high salt concentration could increase their swelling ratio. The loading capacity of PA in PA–CS particles was 82.2?±?1.7 mg/g, and an increased release of PA from the complex occurred at low pH and high salt concentration. After combination, PA–CS complex exhibited better antioxidant activity than CS, which is a result of the synergistic effects of PA and CS. The reducing power and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of PA–CS complex are mainly attributed to PA, whereas the superoxide radical scavenging activity of PA–CS complex largely depends on CS. Moreover, PA–CS complex showed similar diameters of inhibitory zone and identical minimal inhibitory concentrations compared with CS, suggesting that the antibacterial potential of PA–CS complex is similar to that of CS. In addition, after 20 days storage, PA–CS complex did not exhibit significant changes in DPPH radical scavenging activity and antibacterial activity, indicating the good stability of this complex.