Analysis of the resequencing buffer in a homogeneous M/M/2 queue

The resequencing problem is encountered in many practical information systems such as distributed database and communication networks. In these systems customers, such as messages in a computer network, have to be delivered to users in their original order. Therefore, those customers which become out of order due to the randomness of the system are forced to wait in a resequencing buffer so that their delivered order can be guaranteed. The previous work on the resequencing problem mainly concentrated on the delay aspect. From both theoretical and practical viewpoints, however, the queue length characteristics of the resequencing buffer are also significant. We consider the queue length distribution of the resequencing buffer fed by a homogeneous M/M/2 queue. The exact analysis is carried out for the probability mass functions of the queue length in equilibrium and the maximal occupancy which corresponds to the queue length just before the departure instants of customers from the resequencing buffer.     

Absorption and Electrical Conductivity during Electrochemical Reduction in Fullerene Film

The results of in-situ measurements of optical absorption and electrical conductivity in C₆₀/C₇₀ (9/1) film during electrochemical reduction in a cell using solid polymer electrolyte are reported. The drastic change of absorbance and the increase of conductivity upon Li doping were obtained and the results are discussed.     

Inverse systems for reproducing linear functions of inputs

Most of the previous studies on inverse systems have treated only the case where all components of the input of the original system are recoverable. However, even when not all components are recoverable, there is still a possibility of reproducing part of the input. As a generalization of the inverse of a linear time-invariant dynamical system to include such cases, ‘α-integral F-inverse’ is proposed in this paper which reproduces the αth integral of a linear function Fu of the input vector u. A necessary and sufficient condition for the existence of an α-integral F-inverse is derived. A construction procedure of such an inverse is also given along with a numerical example.     

Influence of morphology on photo‐degradation of low density polyethylene films

The effect of the morphology on photo‐degradation was investigated for low‐density polyethylene materials. For this purpose, films with different degrees of crystallinity and different degrees of orientation were prepared. For all the films, photodegradation was promoted at 336K for 12 days using a weather meter. The following results were obtained. There existed an induction period before degradation or chain scission. The induction period was longer for stretched films than for un‐stretched ones. Also, the rate of degradation became lower for stretched films. However, both the induction period and the rate of degradation hardly changed with heat‐treatment condition, that is, the degree of crystallinity. In the induction period, the density changed in a complicated manner. This complicated change must be due to the change in the molecular aggregation state of the amorphous phase. The rheological and GPC measurements indicated that photo‐degradation causes the lowering of molecular weight and the increase in higher molecular weight fraction, and consequently the broadening of molecular weight distribution. The lowering of molecular weight may be caused by chain scission and the increase in higher molecular weight fraction by the formation of crosslinks.     

Tension stiffening effect and bonding characteristics of chemically prestressed concrete under tension

The tension stiffening effect of chemically prestressed concrete (CPC) under uniaxial tension was experimentally investigated and compared with those of reinforced concrete (RC). A special specimen profile was designed to avoid the effect from end parts. The tension stiffening of both RC and CPC were compared with the current tension stiffening model. The crack pattern was observed after loading. The results show that the CPC has superior tension stiffening than RC and the conventional model for RC substantially underestimates the tension stiffening of CPC. In addition, the number of cracks in CPC is less than in RC at the same load. Further investigation on bonding characteristics of CPC under tension was subsequently conducted. Effects of cross section’s size and amount of expansive additive were also investigated. The strain distribution of rebar was measured from strain gages attached with 20 mm interval. Local bond, slip and average bond stress were then calculated. The results show that bond of CPC near loading end is higher than that of RC, although the average bond is almost same. The results of this study can partly explain some of unique tensile properties of CPC which can be related to its cracking resistance.     

日本水文学与水资源研究进展

自1955年以来，日本的经济高速增长导致了工业的快速发展和城区人口的密集，城市的需水量大幅度增加，水资源开发工程建设不可避免地将对自然环境造成影响，因此，对于拟建工程，必须对工程可能对自然环境造成的损害进行调研，在工程建设过程中，应采取适当的措施避免或减小对环境造成的破坏；在工程完工以后，应维持良好的自然环境，近年，根据日本社会和经济的发展，对于河流流域，提出了多种的观点和多重的标准，尤其是生活环境以及生活舒适度已经成为了一个重要的方面，日本政府提出了一个称为“健全的水循环”的新的河流规划，其中包括流域内的水量，水质和生态系统，同时，许多研究者利用地理信息系统，数字高程图，土地利用图，人口分布图等建立了各种分布式径流模型，通过这些信息，能够较容易地获得流域内的长期或短期的水量和水质状况。     

Joint input–output identification of unstable systems with kernel regularization

This paper discusses closed-loop identification of unstable systems. In particular, we first apply the joint input–output identification method and then convert the identification problem of unstable systems into that of stable systems, which can be tackled by using kernel-based regularization methods.We propose to identify two transfer functions by kernel regularization, the one from the reference signal to the input, and the one from the reference signal to the output. Since these transfer functions are stable, kernel regularization methods can construct their accurate models. Then the model of unstable system is constructed by ratio of these functions. The effectiveness of the proposed method is demonstrated by a numerical example and a practical experiment with a DC motor.     

Phylogenetic diversity of microbial communities associated with the crude-oil, large-insoluble-particle and formation-water components of the reservoir fluid from a non-flooded high-temperature petroleum reservoir

The diversity of microbial communities associated with non-water-flooded high-temperature reservoir of the Niibori oilfield was characterized. Analysis of saturated hydrocarbons revealed that n-alkanes in crude oil from the reservoir were selectively depleted, suggesting that crude oil might be mildly biodegraded in the reservoir. To examine if any specific microorganism(s) preferentially attached to the crude oil or the other components (large insoluble particles and formation water) of the reservoir fluid, 16S rRNA gene clone libraries were constructed from each component of the reservoir fluid. The clones in the archaeal libraries (414 clones in total) represented 16 phylotypes, many of which were closely related to methanogens. The bacterial libraries (700 clones in total) were composed of 49 phylotypes belonging to one of 16 phylum-level groupings, with Firmicutes containing the greatest diversity of the phylotypes. In the crude-oil- and large-insoluble-particle-associated communities, a Methanosaeta-related phylotype dominated the archaeal sequences, whereas hydrogenotrophic methanogens occupied a major portion of sequences in the library of the formation-water-associated community. The crude-oil associated bacterial community showed the largest diversity, containing 35 phylotypes, 16 of which were not detected in the other bacterial communities. Thus, although the populations associated with the reservoir-fluid components largely shared common phylogenetic context, a specific fraction of microbial species preferentially attached to the crude oil and insoluble particles.     

Production of epsilon-polylysine in an airlift bioreactor (ABR)

This paper deals with studies on epsilon-poly-L-lysine (epsilon-PL) production in an airlift bioreactor (ABR) using Streptomyces albulus S410 (S410) to minimize the production cost including the downstream processing of epsilon-PL. In a 5-l ABR, 30 g/l of epsilon-PL was produced with a power consumption of 0.3 kW/m3, the production level being similar to that in a 5-l jar fermentor with a power consumption of 8.0 kW/m3. Furthermore, the leakage of intracellular nucleic acid (INA)-related substances into the culture broth in the ABR was less than that in the jar fermentor. Due to the high-level power consumption (8.0 kW/m3) in the jar fermentor, the morphology of the cells changed from the pellet to filament form due to the extensive shear stress arising from continuous agitation, thereby increasing the leakage of the INA-related substances into the culture broth. This suggested that ABR would have an advantage in the low-cost production of epsilon-PL over stirred tank type reactors (STR).