Passive reduction of large pressure variation for a high-speed express train in a narrow tunnel using an extra dummy tunnel duct

When a train travels through tunnel at a high speed, large pressure variations are produced on the train surface by pressure waves. In particular, when an express train travels through a narrow tunnel at a speed higher than that of a conventional train, more severe pressure variations can occur and cause passengers ear discomfort. This paper presents a very simple and effective reduction method of the large pressure variation for a narrow conventional tunnel. When a compression wave and an expansion wave are superposed, the pressure variation can be greatly reduced. Using this phenomenon, this study proposes the construction of a dummy tunnel duct which superposes the pressure waves and reduces the large pressure variation. Using the proposed method, the construction cost is much lower compared to other methods because the dummy tunnel duct can be constructed at the entrance or at the exit of an existing tunnel with a simple tunnel shape. To investigate the change in the maximum pressure difference and pressure variation ratio with the application of a dummy tunnel duct, full-scale tests and numerical analyses were conducted. The results showed that the maximum pressure changes and pressure variation ratio are significantly reduced by a short dummy tunnel duct. From these results, the dummy tunnel duct is expected to be a very economical and practical solution to passenger ear discomfort problems for express trains traveling through conventional narrow tunnels.     

Prospects for the development of oxidative catalysis (On the materials of the ninth international conference EuropaCat-IX, 2009 catalysis for a sustainable world)

This article is an overview of the main results of the section on oxidative catalysis, which is one of the most prospective and intensively developing spheres of catalysis. Basic tendencies and achievements in this field of catalysis are shown, results on the investigation of catalysts used in the synthesis of commercially important products including those of fine organic synthesis are analyzed, and the development of partial oxidation catalytic technologies, the search of new catalysts for these processes, and also the application of deep oxidation processes to the solution of environmental problems are considered. Works concerning the synthesis of catalytic systems based on gold nanoparticles are especially emphasized.     

A modified constrained constant modulus approach to blind adaptivemultiuser detection

An alternative blind adaptive multiuser detection is investigated based on modified constrained constant modulus (CM) criterion. It is shown that the performance of a CM-based receiver is limited by the received power of the desired user. In this paper, we show that the limitation can be avoided using the noncanonical constraint CM criterion and that in the presence of channel noise the modified CM criterion function is strictly convex by properly selecting some constant. With analyzing the extrema of the cost function, we point out how to select the constant. Moreover, a simple stochastic gradient algorithm for implementing our scheme is presented, and the convergence properties of the algorithm are analyzed. Simulation examples are given to demonstrate the performance of the proposed scheme     

Closed-form symbol error rate expression of decode-and-forward relaying using orthogonal space-time block coding

The authors investigate the symbol error rate (SER) performance of the cooperative decode-andforward (DF) relaying strategy with orthogonal space-time block coding (OSTBC) applied at all links of sourcerelay, source-destination and relay-destination. Only when one relay node is able to correctly decode the OSTBC codeword of the source, it will forward source information to the destination with the same OSTBC codeword. The exact SER expressions of DF relaying with OSTBC are presented for M-PSK and M-QAM modulations, respectively, over dissimilar Rayleigh fading channels. By virtue of the multinomial theorem and the law of total probability, the derived expressions are further deduced in closed form. Simulations demonstrate the proposed closed-form analytical results. It is pointed out that such results have seldom appeared in literatures before.     

Guard-Ring Structures for Silicon Photomultipliers

Si photomultipliers with three different guard-ring structures are fabricated, and a detailed comparative study on their device performances is performed. The virtual guard-ring structure shows a high-resolution full width at half maximum in the gamma spectrum and a high breakdown voltage of ~ 66 V but the lowest fill factor of 46.6%-59.8% among the examined structures. The best charge conversion performance, gain, and fill factor (67.1%) are achieved with the trench guard-ring structure. However, this structure shows a low energy resolution, which is supposed to be due to the trench-associated defects. The performance of the N-implantation guard-ring structure is intermediate in most aspects of the device performance compared to the other structures.     

Determination and prediction of Kow and dimensionless Henry's constant (H) for 6 ether compounds at several temperatures

The octanol–water partition coefficient (K_ow) and air–water partition coefficient (K_aw) as well as the dimensionless Henry's constant (H) are used to calculate the transport and fate of chemicals in the environment or eco-system. In this work, the K_ow and the H were measured for 6 ether compounds; di-n-butyl ether (DBE), di-isopropyl ether (DIPE), tert-butyl ethyl ether (ETBE), tert-butyl methyl ether (MTBE), propyl vinyl ether (PVE) and tert-amyl methyl ether (TAME) at 4 different temperatures. The K_ow was directly measured by using a conventional slow stirring (SS) method, while the H was measured using headspace gas chromatography (HSGC). Additionally, the measured K_ow and H values were compared with the predicted values by the fragment constant method or HENRYWIN program approaches.     

Efficient Delivery of Plasmid DNA Using Cholesterol-Based Cationic Lipids Containing Polyamines and Ether Linkages

Cationic liposomes are broadly used as non-viral vectors to deliver genetic materials that can be used to treat various diseases including cancer. To circumvent problems associated with cationic liposome-mediated delivery systems such as low transfection efficiency and serum-induced inhibition, cholesterol-based cationic lipids have been synthesized that resist the effects of serum. The introduction of an ether-type linkage and extension of the aminopropyl head group on the cholesterol backbone increased the transfection efficiency and DNA binding affinity compared to a carbamoyl-type linkage and a mono aminopropyl head group, respectively. Under optimal conditions, each liposome formulation showed higher transfection efficiency in AGS and Huh-7 cells than commercially available cationic liposomes, particularly in the presence of serum. The following molecular structures were found to have a positive effect on transfection properties: (i) extended aminopropyl head groups for a strong binding affinity to plasmid DNA; (ii) an ether linkage that favors electrostatic binding to plasmid DNA; and (iii) a cholesterol backbone for serum resistance.     

Relationship between quality of building maintenance management services for indoor environmental quality and occupant satisfaction

Two surveys were carried out to investigate the correlation between building maintenance management services for indoor environmental quality (IEQ) and occupant satisfaction. Each maintenance management organization manager was surveyed using the Evaluation Index of Maintenance Management Service Quality, created by Akira Takakusagi. Seven office buildings in Seoul, Korea were investigated in the first survey, and two buildings from the first survey were selected for analysis in the second survey. One is a building with good maintenance management services but low occupant satisfaction, and the other is an office building with low maintenance management services but high occupant satisfaction.