Impact force identification by using modal transformation method for automobile test Rig

In the automobile industry, impact force is the main cause for material fatigue in lightweight vehicles. Bump-excited impact force is the most common case, which causes damage to vehicles and reduces the quality of the ride. Force identification is important to reflect the structure's health so that action such as structure modification can be taken before material fatigue. However, direct measurement by using force transducer is not practical due to difficulty in force sensor configuration. A methodology utilizing Operating Deflection Shape (ODS) analysis, Frequency Response Function (FRF) measurement and Modal Transformation Method (MTM) to evaluate the dynamic force is proposed here. This method is called indirect force measurement by using inverse technique. The performance of this approach was demonstrated via experiment. From the measured responses and measured dynamic characteristics of an automobile test rig, a real time mathematical manipulation can generate the system's input force. The force location is known in priori for impact excitation and therefore the inverse problem is well-posed. This method was tested using different force location with unique input force. It shows that high quality of curve fitting to extract the modal parameters such as damped natural frequency, modal damping and residue mode shape is essential to obtain a high accuracy force determination © (2014) Trans Tech Publications, Switzerland

Hybrid pitch angle controller approaches for stable wind turbine power under variable wind speed

The production of maximum wind energy requires controlling various parts of medium to large-scale wind turbines (WTs). This paper presents a robust pitch angle control system for the rated wind turbine power at a wide range of simulated wind speeds by means of a proportional–integral–derivative (PID) controller. In addition, ant colony optimization (ACO), particle swarm optimization (PSO), and classical Ziegler–Nichols (Z-N) algorithms have been used for tuning the PID controller parameters to obtain within rated stable output power of WTs from fluctuating wind speeds. The proposed system is simulated under fast wind speed variation, and its results are compared with those of the PID-ZN controller and PID-PSO to verify its effeteness. The proposed approach contains several benefits including simple implementation, as well as tolerance of turbine parameters and several nonparametric uncertainties. Robust control of the generator output power with wind-speed variations can also be considered a significant advantage of this strategy. Theoretical analyses, as well as simulation results, indicate that the proposed controller can perform better in a wide range of wind speed compared with the PID-ZN and PID-PSO controllers. The WT model and hybrid controllers (PID-ACO and PID-PSO) have been developed in MATLAB/Simulink with validated controller models. The hybrid PID-ACO controller was found to be the most suitable in comparison to the PID-PSO and conventional PID. The root mean square (RMS) error calculated between the desired power and the WT’s output power with PID-ACO is found to be 0.00036, which is the smallest result among the studied controllers

Importance of Selecting a Suitable Analysis Frequency Range in Impact Force Identification for Automobile Test Rig

In this study, the effectiveness of selecting a suitable analysis frequency range in impact force identification is highlighted. A methodology that utilizesOperating Deflection Shape (ODS) analysis, Modal Analysis (MA) and Modal Transformation Method (MTM) to evaluate the dynamic force in three cases of analysis frequency ranges was presented. These three cases are the overestimated, even-estimated, and under-estimated cases, which consist of higher, similar andlower analysis frequency range respectively, compared to the actual excitation frequency range. The performance of this approach was demonstrated via experiment. A Perspex plate with four ground supports was used as the automobile test rig. By measuring the acceleration response and Frequency Response Function (FRF) of the test rig, the time history of unknown force was recovered by the proposed method where the impact location was known in advance. It showed that the force identification result for even-estimated case falls within acceptable range while the force identification result for over-estimated and under-estimated cases isnot acceptable

Information-Based Hierarchical Planning for a Mobile Sensing Network in Environmental Mapping

This article investigates the problem of information-based sampling design and path planning for a mobile sensing network to predict scalar fields of monitored environments. A hierarchical framework with a built-in Gaussian Markov random field model is proposed to provide adaptive sampling for efficient field reconstruction. In the proposed framework, a nonmyopic planner is operated at a sink to navigate the mobile sensing agents in the field to the sites that are most informative. Meanwhile, a myopic planner is carried out on board each agent. A tradeoff between computationally intensive global optimization and efficient local greedy search is incorporated into the system. The mobile sensing agents can be scheduled online through an anytime algorithm to visit and observe the high-information sites. Experiments on both synthetic and real-world datasets are used to demonstrate the feasibility and efficiency of the proposed planner in model exploitation and adaptive sampling for environmental field mapping

Aldose Reductase Genotypes and Cardiorenal Complications: An 8-year prospective analysis of 1,074 type 2 diabetic patients

OBJECTIVE—We report the independent risk association of type 2 diabetic nephropathy with the z−2 allele of the 5′-(CA)n microsatellite and C-106T promoter polymorphisms of the aldose reductase gene (ALR2) using a case-control design. In this expanded cohort, we examined their predictive roles on new onset of cardiorenal complications using a prospective design

Metabolic Syndrome Predicts New Onset of Chronic Kidney Disease in 5,829 Patients With Type 2 Diabetes: A 5-year prospective analysis of the Hong Kong Diabetes Registry

OBJECTIVE—Type 2 diabetes is the leading cause of end-stage renal disease worldwide. Aside from hyperglycemia and hypertension, other metabolic factors may determine renal outcome. We examined risk associations of metabolic syndrome with new onset of chronic kidney disease (CKD) in 5,829 Chinese patients with type 2 diabetes enrolled between 1995 and 2005

Fibroblastic niches prime T cell alloimmunity through Delta-like Notch ligands.

Alloimmune T cell responses induce graft-versus-host disease (GVHD), a serious complication of allogeneic bone marrow transplantation (allo-BMT). Although Notch signaling mediated by Delta-like 1/4 (DLL1/4) Notch ligands has emerged as a major regulator of GVHD pathogenesis, little is known about the timing of essential Notch signals and the cellular source of Notch ligands after allo-BMT. Here, we have shown that critical DLL1/4-mediated Notch signals are delivered to donor T cells during a short 48-hour window after transplantation in a mouse allo-BMT model. Stromal, but not hematopoietic, cells were the essential source of Notch ligands during in vivo priming of alloreactive T cells. GVHD could be prevented by selective inactivation of Dll1 and Dll4 in subsets of fibroblastic stromal cells that were derived from chemokine Ccl19-expressing host cells, including fibroblastic reticular cells and follicular dendritic cells. However, neither T cell recruitment into secondary lymphoid organs nor initial T cell activation was affected by Dll1/4 loss. Thus, we have uncovered a pathogenic function for fibroblastic stromal cells in alloimmune reactivity that can be dissociated from their homeostatic functions. Our results reveal what we believe to be a previously unrecognized Notch-mediated immunopathogenic role for stromal cell niches in secondary lymphoid organs after allo-BMT and define a framework of early cellular and molecular interactions that regulate T cell alloimmunity

Additive Interaction of Hyperglycemia and Albuminuria on Risk of Ischemic Stroke in Type 2 Diabetes: Hong Kong Diabetes Registry

OBJECTIVE—The study aims to test whether biological interaction between hyperglycemia and albuminuria can explain the inconsistent findings from epidemiological studies and clinical trials about effects of hyperglycemia on stroke in type 2 diabetes