Niigata, Japan

Niigata Institute of Technology is a private university in Kashiwazaki, Niigata, Japan. It was established in 1995. Wikipedia.


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Yoshimoto Y.,Niigata Institute of Technology | Kinoshita E.,Kagoshima University | Shanbu L.,Niigata Institute of Technology | Ohmura T.,Niigata Diamond Electronic Co Ltd
Energy | Year: 2013

PME (Palm oil methyl ester) is a promising alternative fuel among biodiesels, because palm oil is the most produced feedstock and its yield is the highest among vegetable oil crops. However, PME has a serious drawback in its relatively high pour point. The aim of this investigation is to extend the range of utilization of PME by improving its low temperature fluidity. The present study used three kinds of blended fuels composed of PME/gas oil/1-butanol to show the effect of lower pour points. Neat PME has a pour point of 19°C, for a PME blend with 20% PME (PME20) the pour point is-5°C, and with 40 mass% 1-butanol blended into the PME20 the pour point is-10°C. Using four kinds of PME/gas oil blends as the base fuels the influence of 1-butanol addition on the engine performance, combustion characteristics, and exhaust emissions of a small single cylinder DI (direct injection) diesel engine was examined. The brake thermal efficiency of the base fuels changed little when 1-butanol was added up to 40 mass%. The results also showed that at the rated output condition the smoke emissions decreased considerably with increasing 1-butanol addition ratios. © 2012 Elsevier Ltd.


Tominaga Y.,Niigata Institute of Technology | Stathopoulos T.,Concordia University at Montréal
Atmospheric Environment | Year: 2013

Near-field pollutant dispersion in the urban environment involves the interaction of a plume and the flow field perturbed by building obstacles. In the past two decades, micro-scale Computational Fluid Dynamics (CFD) simulation of pollutant dispersion around buildings and in urban areas has been widely used, sometimes in lieu of wind tunnel testing. This paper reviews current modeling techniques in CFD simulation of near-field pollutant dispersion in urban environments and discusses the findings to give insight into future applications. Key features of near-field pollutant dispersion around buildings from previous studies, i.e., three-dimensionality of mean flow, unsteadiness of large-scale flow structure, and anisotropy of turbulent scalar fluxes, are identified and discussed. This review highlights that it is important to choose appropriate numerical models and boundary conditions by understanding their inherent strengths and limitations. Furthermore, the importance of model evaluation was emphasized. Because pollutant concentrations around buildings can vary by orders of magnitudes in time and space, the model evaluation should be performed carefully, while paying attention to their uncertainty. Although CFD has significant potential, it is important to understand the underlying theory and limitations of a model in order to appropriately investigate the dispersion phenomena in question. © 2013 Elsevier Ltd.


Tominaga Y.,Niigata Institute of Technology | Stathopoulos T.,Concordia University at Montréal
Journal of Wind Engineering and Industrial Aerodynamics | Year: 2011

CFD modeling using RANS and LES of pollutant dispersion in a three-dimensional street canyon is investigated by comparison with measurements. The purpose of this study is to confirm the accuracy of LES in modeling plume dispersion in a simple street canyon model and to clarify the mechanism of the discrepancy in relation to RANS computation. Simple LES modeling is shown by comparison with wind tunnel experiments to give better results than conventional RANS computation (RNG) modeling of the distribution of mean concentration. The horizontal diffusion of concentration is well reproduced by LES, mainly due to the reproduction of unsteady concentration fluctuations in the street canyon. © 2010 Elsevier Ltd.


Tominaga Y.,Niigata Institute of Technology | Stathopoulos T.,Concordia University at Montréal
Building and Environment | Year: 2010

Several studies have been carried out on CFD prediction based on a RANS (Reynolds Averaged Navier-Stokes equations) model for dispersion around buildings, but it was reported that a RANS computation often provides extremely high concentration, which are not observed in usual measurements. These results suggest that transient simulations such as the large-eddy simulation (LES) might be required to achieve more accurate results. Nevertheless, very few studies have evaluated the basic performance of LES in modeling the dispersion field for a simple configuration in comparison with the RANS model. Therefore, relative performance of these simulation methods for dispersion problem around buildings should be clarified in order to make it possible to choose a suitable numerical method for its purpose. The purpose of this study is to confirm the accuracy of LES in modeling plume dispersion near and around a simple building model and to clarify the mechanism for the discrepancy in relation to the RANS computation. Simple LES modeling gives better results than RNG modeling of the distribution of concentration, although the difference for mean velocity is not so large. The horizontal diffusion of concentration is well reproduced by LES. This tendency is closely related to the reproduction of unsteady periodic fluctuation around cubical forms in LES. © 2010 Elsevier Ltd.


Hotta Y.,Niigata Institute of Technology
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2011

This study assessed muscle fatigue during low-level contraction, which is sometimes difficult to observe. Surface EMG signals were recorded with monopolar and bipolar configurations during low-level isometric muscle contraction under a blood flow restriction condition (BFR condition) and a non-blood flow restriction condition (CON condition). As indices of fatigue, center frequency (CF) of the power spectral density (PSD) of the surface EMG and rating of perceived exertion (RPE) with the Borg CR-10 Scale were used. Results suggested that the monopolar configuration, which has a wider detection area relative than the bipolar one, was well suited for obtaining wave slowing accompanied by muscle fatigue. In addition, the monopolar configuration could detect differences in muscle condition in the BFR and CON conditions.


Tominaga Y.,Niigata Institute of Technology | Stathopoulos T.,Concordia University at Montréal
Journal of Wind Engineering and Industrial Aerodynamics | Year: 2012

Modeling of turbulent scalar flux in CFD (Computational Fluid Dynamics) for near-field dispersion around buildings is examined by investigating both velocity and concentration fields obtained by two modeling approaches, i.e., RANS RNG k-ε and LES. A building array model with a point source located in between the central buildings is adopted as a target configuration. First, the prediction accuracy of LES is confirmed by comparing with the RNGcomputation and the results from an experiment conducted by the authors. LES gives better results than RNG, in terms of time-averaged velocity and concentration distribution in comparison with the wind tunnel experimental results. Next, the eddy viscosity and the eddy diffusivity are determined by LES data using a least square approach as suggested in the dynamic sub-grid scale model. Large differences can be observed between the distributions of the estimated eddy viscosity by using LES data and the eddy diffusivity obtained by RNG, since the eddy diffusivity is not always proportional to the eddy viscosity. © 2012 Elsevier Ltd.


Yoshimoto Y.,Niigata Institute of Technology
Nihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B | Year: 2010

This paper investigates the performance, exhaust emissions, and combustion characteristics of a dual fuel diesel engine fueled by CNG (Compressed Natural Gas) as the main fuel. The experiments used two fuels for the ignition: one is OME (Oléate Methyl Ester), a major component of biodiesel, and the other is ordinary gas oil. The CNG supply rate was defined as the heat energy ratio of the supplied CNG to the total heat energy available in the cylinder. The results show that the conditions where operation with CNG/OME is possible are very similar to those of CNG/gas oil. When the CNG supply rate was raised to 75%, the brake thermal efficiency was similar to that of ordinary diesel operation at BMEP=0.65 MPa. When the CNG supply rate was higher than 75% ignition became very unstable and the brake thermal efficiency decreased significantly as well as the HC and NOx emissions increased sharply. The reason for this is considered to be that the appearance of miss fire cycles gave rise to combustion fluctuations.


This paper investigates the performance, exhaust emissions, and combustion characteristics of a dual fuel diesel engine fueled by CNG (compressed natural gas) as the main fuel. The experiments used a small single cylinder DI diesel engine and two kinds of fuels for the ignition: FAME (fatty acid methyl ester) fuels such as Methyl Oleate (OME) and OME-Methyl Palmitate (PME) blends, major components of biodiesel, and ordinary gas oil. The rate of the CNG supply was defined as the proportion of the heat energy of the supplied CNG to the total heat energy available in the cylinder. Compared with gas oil ignition, the FAME fuels had shorter ignition delays and significantly reduced smoke densities regardless of the PME contents. The PME contained in the FAME fuels gave rise to slight improvements in ignitability. The results also showed that the conditions where operation with CNG/FAME fuels is possible are very similar to those of the CNG/gas oil. When the CNG supply rate was raised to 75%, the brake thermal efficiency was similar to that of ordinary diesel operation at BMEP=0.67MPa. When the CNG supply rate was higher than 75% ignition became very unstable and the brake thermal efficiency decreased significantly as well as the HC and NOx emissions increased sharply. The reason for this is considered to be the appearance of misfiring, which gives rise to combustion fluctuations. Copyright © 2010 SAE International and Copyright © 2010 SAE Japan.


Ito K.,Niigata Institute of Technology
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2012

The center frequency (CF) of the power spectral density of a bipolar-configured surface electromyogram is typically used as an index of muscle fatigue. However, this index may be inadequate for measuring wave slowing due to muscle fatigue during low-level contractions. A previous study in which strong muscle fatigue was mimicked by compressing the proximal region of the forearm during isometric contractions showed that the differences in the degree of fatigue under compression and non-compression conditions were undetectable. The purpose of this study was to improve detection sensitivity of surface EMG variation caused by muscle fatigue using two approaches. The first approach employed recurrence quantification analysis (RQA) instead of traditional frequency analysis (FA) to compute the muscle fatigue index. The second approach employed a monopolar configuration for measuring surface EMG. We measured the surface EMG signal by using monopolar and bipolar configurations simultaneously during low-level isometric contractions under blood flow-restricted (BFR) and unrestricted (CON) conditions, and then compared and evaluated the detected differences in muscle fatigue. The results showed that the effect of BFR was better detected by RQA than by FA, and that the fatigability change was larger in the monopolar configuration than in the bipolar configuration.


Patent
Niigata Institute of Technology and Daiwa Can Company | Date: 2011-06-22

The present invention provides a food sterilization method by which the effective sterilization of the spore-forming bacteria having high heat resistance and high pressure resistance is possible without impairing the taste, flavor, and texture of food. A method for sterilization of food comprising: high-pressure treatment step in which one or more amino acids selected from the group consisting of cysteine, alanine, methionine, phenylalanine, serine, leucine, and glycine is added to a sterilization target food, and then the sterilization target food including the amino acid is treated at 50 to 600 MPa for 1 to 120 minutes; and low-temperature heating step in which the sterilization target food is heated at 60 to 100 C. for 5 minutes or more after the high-pressure treatment step.

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