Hideki Takamatsu

Design of a robust controller for shift control of an automatic transmission

A robust controller is proposed for the clutch-to-clutch shift of a stepped-ratio automatic transmission. The control strategy consists of three parts: a feedback controller is derived using µ synthesis, which guarantees the system robustness; a feedforward controller is designed to improve the tracking performance; a disturbance compensator is used to reduce the effect of the disturbance on the system output. Finally the designed controller is tested on a powertrain simulation model, which contains a complete drivetrain and clutch actuators. It is demonstrated that the controller is robust against uncertainties in the parameters and variations in the driving conditions. Moreover, discrete implementations with a sampling time of 10 ms show the potential of the proposed controller for use in real vehicles.

PSO-based model identification of a full-scale CVT drivetrain

Torque transfer characteristics of the drivetrain of a production continuously variable transmission (CVT) vehicle is identified based on a particle swarm optimization (PSO) technique. The torque transfer characteristics from the CVT input shaft to the driveshaft is described by a simple nonlinear model: a single degree-of-freedom vibration model with a clearance. Based on the full-scale experimental data, the model parameters are identified by a data correction method and PSO. The simulated driveshaft torque shows good agreement with the measured torque from the experiment.

Association between kidney function and genetic polymorphisms in atherosclerotic and chronic kidney diseases: A cross-sectional study in Japanese male workers.

Background Several single nucleotide polymorphisms (SNPs) have been implicated in the predisposition to chronic kidney disease (CKD). Atherosclerotic disease is deeply involved in the incidence of CKD; however, whether SNPs related to arteriosclerosis are involved in CKD remains unclear. This study aimed to identify SNPs associated with CKD and to examine whether risk allele accumulation is associated with CKD. Methods We conducted a cross-sectional study using data of 4814 male workers to examine the association between estimated glomerular filtration rate (eGFR) and 59 candidate polymorphisms (17 CKD, 42 atherosclerotic diseases). We defined the genetic risk score (GRS) as the total number of risk alleles that showed a significant association in this analysis and examined the relationship with CKD (eGFR < 60 ml/min/1.73m2). Multivariate logistic regression, discrimination by area under the receiver operating characteristic curve, integrated discrimination improvement (IDI), and category-free net reclassification improvement (cNRI) were evaluated. Results In total, 432 participants were categorized as having CKD. We found eight candidate SNPs with P value < 0.05 (CX3CR1 rs3732379, SHROOM3 rs17319721, MTP rs1800591, PIP5K1B rs4744712, APOA5 rs662799, BRAP rs3782886, SPATA5L1 rs2467853, and MCP1 rs1024611) in the multivariate linear regression adjusted for age, body mass index, systolic blood pressure, and fasting blood glucose. Among these eight SNPs, BRAP rs3782886 and SPATA5L1 rs2467853 were significantly associated with eGFR (false discovery rate < 0.05). GRS was significantly associated with CKD (odds ratio, 1.17; 95% confidence interval, 1.09–1.26). C-statisics improved from 0.775 to 0.780 but showed no statistical significance. However, adding GRS significantly improved IDI and cNRI (0.0057, P = 0.0028, and 0.212, P < 0.001, respectively). Conclusions After adjustment for clinical factors, kidney function was associated with BRAP rs3782886 and SPATA5L1 rs2467853 and the GRS for CKD that we developed was associated CKD.

Effect of dietary energy and polymorphisms in BRAP and GHRL on obesity and metabolic traits

OBJECTIVE Obesity, a risk factor for all-cause and cardiovascular mortality, is a major health concerns among middle-aged men. The aim of this study was to investigate a possible association of dietary habits and obesity related single nucleotide polymorphisms (SNPs) with obesity and metabolic abnormalities. METHODS We conducted a retrospective cohort study using annual health examination data of 5112 male workers, obtained between 2007 and 2011. Average dietary energy was estimated using electronically collected meal purchase data from cafeteria. We examined 8 SNPs related to obesity: GHRL rs696217, PPARG rs1175544, ADIPOQ rs2241766, ADIPOQ rs1501299, PPARD rs2016520, APOA5 rs662799, BRAP rs3782886, and ITGB2 rs235326. We also examined whether SNPs that were shown to associate with obesity affect other metabolic abnormalities such as blood pressure (BP), glucose, and lipid profile. RESULTS Average dietary energy significantly associated with increased abdominal circumference (AC) and body mass index (BMI). The odds ratios (ORs) of overweight and obesity also increased. The major allele of rs696217 significantly increased BMI and an increased OR with obesity, while the minor allele of rs3782886 was associated with significantly decreased AC and the decreased ORs with overweight and obesity. The minor allele of rs3782886 was also associated with significantly decreased systolic BP (SBP), triglyceride (TG), high-density lipoprotein (HDL), and fasting blood sugar (FBS), while rs696217 was not associated with other metabolic abnormalities. CONCLUSIONS Average dietary energy in lunch, rs3782886, and rs696217 were associated with obesity, and rs3782886 was associated with other metabolic abnormalities.