ファンから生じる空力騒音の予測と低減に関する計算的研究

Turbomachinery is machinery device in which energy is delivered either to or from fluid that is continuously moving due to action of moving blades. Performance and flow noise are two major indices for evaluation of turbomachinery. In terms of energy transfer, researches on performance of turbomachinery have been conducted since long time ago; and these researches for performance improvement are still ongoing currently. In addition, flow noise produced by turbomachinery came to the fore as turbomachinery has been used in various fields and everyday life closely and frequently. Especially, consumers’ demand on improvement in affective quality has been increased and regulation on noise has been being reinforced due to damages and adverse effects caused by noise. Therefore, development of high performance and low noise turbomachinery is highly required. Meanwhile, experimental methods have been used to develop low noise turbomachinery; however, the experimental methods solely are not sufficient to achieve such aim since measuring in small turbomachinery is challenging. Hence, prediction technique, to which the numerical analysis method that yields complementary effects in combination with the experimental methods is applied, is required. This study was conducted with the aim of applying numerical analysis method for noise reduction in turbomachinery. Therefore, three-dimensional unsteady Navier-Stokes equations were solved to simulate the flow field. Turbulence models used to predict the flow field were SST k–ω model that provides outstanding simulation of separation and adverse pressure gradient in boundary layer and LES model that presents excellence in turbulence intensity modeling, respectively. Computational Aeroacoustics (CAA) used to predict the flow noise in this study was acoustic analogy that is one of the hybrid methods; and the acoustic analogy is the method analyzing unsteady flow field by using Computational Fluid Dynamics (CFD) and then predicting noise by using the information of unsteady flow field obtained from the results of CFD simulation. To conduct acoustic analogy, Lowson equation, which can be used to predict sound pressure for point force that is moving in a free field, was calculated. Despite of disadvantage that influence of an object including scattering, diffraction, and reflection within acoustic field is difficult to be considered, this method that directly reduces noise sources was able to be drawn since the locations of the noise source can be seen by numerical approach. Because predicting the location of the noise source is able to figure out the unsteady flow which causes the noise. As a result, the reduction method of flow-induced noise in this study is to find the way to reduce or remove the unsteady flow generating the noise, based on CAA and CFD. In order to indicate the location of the noise source, “Aeroacoustic source strength, Ast” was defined and compared with the location of the noise source measured by the acoustic camera to which beamforming technology is applied; and they were agreed qualitatively well each other. Due to miniaturization of electronics and maintenance of fan performance, whereas size of fan is getting smaller, the rotational speed of it getting higher. In this study following the current trend, three fans with each other different type were used for adopting numerical method to noise reduction; ⅰ) a small axial fan of rotor’s diameter D = 0.166 m and a rotation speed 2860 rpm with circular shroud, ⅱ) a small axial fan of rotor’s diameter D = 0.076 m and a rotation speed 7000 rpm with square-type shroud used in a rack mount server computer, ⅲ) a small centrifugal fan with rotor’s diameter D = 0.032 m and a rotation speed 10460 rpm used as a cooling fan in portable home electronics such as a small laptop computer. The noise of each type fan was predicted and compared with the measured noise. The predicted noise and measured noise presented agreement in tonal noise of the blade passing frequency (BPF) and its harmonic frequencies and in the broadband noise at low frequency. Although the broadband noise at high frequency was somewhat different due to random broadband noise, the shapes for noise reduction were able to be drawn effectively by predicting the location of the noise sources. Low noise models suggested for noise reduction provided the result of noise reduction from the prediction and specific noise level was used to evaluate the noise reduction considering the changes in fan performance. In case of the axial flow fan with circular shroud, the interaction between the rotating rotor blades and the flow separated from the inlet of the shroud was found to be the major cause of the noise through the analysis on the location of the noise sources and unsteady flow field. Consequently, reduction of the flow noise was predicted by correcting the shape of the shroud inlet. In the small axial flow fan installed in the rack mount server computer, the tonal noise occurring by irregular clearance between the blade tip and the shroud due to the square-shaped shroud was well predicted. In addition, coherence analysis was conducted to identify the relationship between the surface pressure fluctuation due to the flow and the sound pressure predicted from the microphone. As a result, the correlation for each frequency was well presented. For a centrifugal fan that is used as a cooling fan in home electronics such as a portable small laptop computer, the flow structure of the centrifugal fan was simulated by setting the condition to be analogous to the operating condition within the actual product. And then the reduction of the flow noise was predicted by correcting the tip of the impeller blades based on the location of the noise sources. This study aimed to apply the method of numerical analysis to the noise reduction in turbomachinery. For this, the unsteady flow field was analyzed, the result of noise prediction obtained from the flow filed information was compared and validated, and the location of the noise sources and the structure of the flow field causing the noise were understood; hence, the low noise design was able to be drawn effectively and properly. In this study, the reduction of the flow noise was successfully achieved by adopting the method of numerical analysis and the flow noise of the fan that were improved for noise reduction was predicted to be reduced by 0.8 and 3.7 dB, respectively.博士(工学)法政大学 (Hosei University

Gastrointestinal Complications Following Hematopoietic Stem Cell Transplantation in Children

Gastrointestinal system involvement is one of the principal complications seen in the recipients of hematopoietic stem cell transplantation (HSCT), and it is also a major cause of morbidity and death in these patients. The major gastrointestinal complications include typhlitis (neutropenic enterocolitis), pseudomembranous enterocolitis, viral enteritis, graft-versus-host disease, benign pneumatosis intestinalis, intestinal thrombotic microangiopathy, and post-transplantation lymphoproliferative disease. As these patients present with nonspecific abdominal symptoms, evaluation with using such imaging modalities as ultrasonography and CT is essential in order to assess the extent of gastrointestinal involvement and to diagnose these complications. We present here a pictorial review of the imaging features and other factors involved in the diagnosis of these gastrointestinal complications in pediatric HSCT recipients

The Mildly Elevated Serum Bilirubin Level is Negatively Associated with the Incidence of End Stage Renal Disease in Patients with IgA Nephropathy

Oxidative stress plays various roles in the development and progression of IgA nephropathy, while bilirubin is known as a potent antioxidant. We therefore hypothesized that serum bilirubin would be associated with renal prognosis in IgA nephropathy. The study subjects comprised 1,458 adult patients with primary IgA nephropathy in Korea. We grouped patients according to the following quartile levels of bilirubin: <0.4 mg/dL (Q1), 0.4-0.5 mg/dL (Q2), 0.6-0.7 mg/dL (Q3), and >0.8 mg/dL (Q4). The outcome data were obtained from the Korean Registry of end-stage renal disease (ESRD). Eighty patients (5.5%) contracted ESRD during a mean follow-up period of 44.9 months. The ESRD incidences were 10.7% in Q1, 8.2% in Q2, 2.8% in Q3, and 2.8% in Q4 (p<0.001). The relative risk of ESRD compared to that in Q1 was 0.307 (95% confidence interval [CI], 0.126-0.751) in Q3 and 0.315 (95% CI, 0.130-0.765) in Q4. The differences of ESRD incidence were greater in subgroups of males and of patients aged 35 yr or more, with serum albumin 4.0 g/dL or more, with normotension, with eGFR 60 mL/min/1.73 m2 or more, and with proteinuria less then 3+ by dipstick test. In conclusion, higher bilirubin level was negatively associated with ESRD incidence in IgA nephropathy

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

Search for supersymmetry in events with one lepton and multiple jets in proton-proton collisions at root s=13 TeV

Peer reviewe