System Configuration and Control Using Hydraulic Transformer

University of Minnesota Ph.D. dissertation. May 2018. Major: Mechanical Engineering. Advisor: Perry Li. 1 computer file (PDF); xii, 294 pages.Hydraulic power transmission offers multiple benefits over competing technologies including an order of magnitude higher power density than electric systems, relatively low cost, fast response, and flexible packaging. Hydraulics are often used in high-performance mobile robots that demand power, precision, and compactness. However, typical hydraulic systems suffer from low system efficiency from the wide usage of throttle valves. The research described in this dissertation focuses on developing hydraulic transformers that transforms hydraulic power from one set of pressure and flow to the other set of pressure and flow to replace throttle valves such that a compact and efficient fluid power system can be realized. A dynamic model capable of capturing operating characteristics and losses is developed to establish a quantitative comparison between two major designs of the hydraulic transformer. A traditional design where a pump and motor are coupled together in a single package is chosen for the research. This design has three possible configurations with unique operating characteristics, and if these configuration modes can be switched, the resulting transformer is shown to be more compact and efficient. A trajectory tracking controller for a cylinder and force controller for a hydraulic human power amplifier is developed to demonstrate potential applications for the hydraulic transformer. The controller developed proves that utilizing hydraulic transformer need not sacrifice the control performance. Control methodologies ensuring efficiency of the transformer driven system are developed. Transformer operating speed is optimized to minimize the power loss through the transformer. Transformer configuration is switched actively to operate the transformer in its most optimal mode. These methods further improve the efficiency benefit of using the transformer. A hydraulic transformer system utilizing developed controllers compared against a throttle valve system tracking a trajectory with various loading conditions reveals that transformer system can achieve an efficiency of 81.2% which is more than threefold increase over the throttling system with an efficiency of 26.2%. This efficiency improvement is possible with the ability of a transformer to capture regenerative energy to reduce the net energy consumption. This dissertation successfully presents the controller development for a hydraulic transformer that captures both precision and efficiency

Characterization of thiobarbituric acid derivatives as inhibitors of hepatitis C virus NS5B polymerase

In an effort to find chemicals inhibiting the enzymatic activity of the hepatitis C virus (HCV) NS5B polymerase, a series of thiobarbituric acid derivatives were selected from a library provided by Korea Research Institute of Chemical Technology and characterized. The selected compounds exhibited IC50 values ranging from 1.7 to 3.8 μM, and EC50 values ranging from 12.3 to 20.7 μM against NS5B polymerase of type 1b strain. They showed little effect against type 2a polymerase. One of the compounds, G05, was selected and further characterized. It inhibited the synthesis of RNA by recombinant HCV NS5B polymerase in a dose dependent manner. The CC50 value was 77 μM. The inhibition was in a noncompetitive manner with the substrate UTP. The compound did not inhibit the elongation step of RNA synthesis in a single-cycle processive polymerization assay. It inhibited the binding of NS5B polymerase to the template RNA in a dose-dependent manner

韓国の河川水資源の特性と水田開発

筑波大学 (University of Tsukuba)201

A Study on the Thermal Characteristics of the Epoxy Insulator in the Stop Joint Box of HTS Power Cable

AbstractThe HTS power cable is cooled by the circulation of liquid nitrogen. The cooling capacity of refrigerator increases with cable length. As the length of power cable increases, a joint box should be installed to reduce the cooling capacity and pressure drop for unit cooling system. The type of joint box can be divided into two groups. There are NJB(Normal Joint Box) and SJB(Stop Joint Box). Generally, SJB can separate each cooling system. In case of long distance DC cable, it is necessary to separate the cooling line in the regular distance of cooling system so SJB should be used. However, SJB, which has a difference from the insulation method of existing joint box, uses solid electrical insulation method. At the primary cooling time, thermal stress is generated by the temperature difference between the internal and external epoxy. So to prevent the damage stress analysis is required for the electrical insulation structure of SJB. In this paper, using the FEM analysis we study the cooling method and optimal shape of SJB to reduce the thermal stress result from temperature difference during the cooling time

Fine-Grained Socioeconomic Prediction from Satellite Images with Distributional Adjustment

While measuring socioeconomic indicators is critical for local governments to make informed policy decisions, such measurements are often unavailable at fine-grained levels like municipality. This study employs deep learning-based predictions from satellite images to close the gap. We propose a method that assigns a socioeconomic score to each satellite image by capturing the distributional behavior observed in larger areas based on the ground truth. We train an ordinal regression scoring model and adjust the scores to follow the common power law within and across regions. Evaluation based on official statistics in South Korea shows that our method outperforms previous models in predicting population and employment size at both the municipality and grid levels. Our method also demonstrates robust performance in districts with uneven development, suggesting its potential use in developing countries where reliable, fine-grained data is scarce

Sequential activation of human signal recognition particle by the ribosome and signal sequence drives efficient protein targeting

Signal recognition particle (SRP) is a universally conserved targeting machine that mediates the targeted delivery of ∼30% of the proteome. The molecular mechanism by which eukaryotic SRP achieves efficient and selective protein targeting remains elusive. Here, we describe quantitative analyses of completely reconstituted human SRP (hSRP) and SRP receptor (SR). Enzymatic and fluorescence analyses showed that the ribosome, together with a functional signal sequence on the nascent polypeptide, are required to activate SRP for rapid recruitment of the SR, thereby delivering translating ribosomes to the endoplasmic reticulum. Single-molecule fluorescence spectroscopy combined with cross-complementation analyses reveal a sequential mechanism of activation whereby the ribosome unlocks the hSRP from an autoinhibited state and primes SRP to sample a variety of conformations. The signal sequence further preorganizes the mammalian SRP into the optimal conformation for efficient recruitment of the SR. Finally, the use of a signal sequence to activate SRP for receptor recruitment is a universally conserved feature to enable efficient and selective protein targeting, and the eukaryote-specific components confer upon the mammalian SRP the ability to sense and respond to ribosomes

Effects of multicomponent exercise on cognitive function in older adults with amnestic mild cognitive impairment: a randomized controlled trial

BACKGROUND: To examine the effects of a multicomponent exercise program on the cognitive function of older adults with amnestic mild cognitive impairment (aMCI). METHODS: Design: Twelve months, randomized controlled trial; Setting: Community center in Japan; Participants: Fifty older adults (27 men) with aMCI ranging in age from 65 to 93 years (mean age, 75 years); Intervention: Subjects were randomized into either a multicomponent exercise (n = 25) or an education control group (n = 25). Subjects in the multicomponent exercise group exercised under the supervision of physiotherapists for 90 min/d, 2 d/wk, for a total of 80 times over 12 months. The exercises included aerobic exercises, muscle strength training, and postural balance retraining, and were conducted using multiple conditions to stimulate cognitive functions. Subjects in the control group attended three education classes regarding health during the 12-month period. Measurements were administered before, after the 6-month, and after the 12-month intervention period; Measurements: The performance measures included the mini-mental state examination, logical memory subtest of the Wechsler memory scale-revised, digit symbol coding test, letter and categorical verbal fluency test, and the Stroop color word test. RESULTS: The mean adherence to the exercise program was 79.2%. Improvements of cognitive function following multicomponent exercise were superior at treatment end (group × time interactions for the mini-mental state examination (P = 0.04), logical memory of immediate recall (P = 0.03), and letter verbal fluency test (P = 0.02)). The logical memory of delayed recall, digit symbol coding, and Stroop color word test showed main effects of time, although there were no group × time interactions. CONCLUSIONS: This study indicates that exercise improves or supports, at least partly, cognitive performance in older adults with aMCI

A Large, Cross-Sectional Observational Study of Serum BDNF, Cognitive Function, and Mild Cognitive Impairment in the Elderly

Objective: The clinical relationship between brain-derived neurotrophic factor (BDNF) and cognitive function or mild cognitive impairment (MCI) is not well understood. The purpose of this study was to identify the relationship between serum BDNF and cognitive function and MCI, and determine whether serum BDNF level might be a useful biomarker for assessing risk for MCI in older people.Materials and Methods: A total of 4463 individuals aged 65 years or older (mean age 72 years) participating in the study. We measured performance in a battery of neuropsychological and cognitive function tests; serum BDNF concentration.Results: Eight hundred twenty-seven participants (18.8%) had MCI. After adjustment for sex, age, education level, diabetes, and current smoking, serum BDNF was associated with poorer performance in the story memory, and digit symbol substitution task scores. Serum BDNF was marginally associated with the presence of MCI (OR, 95% CI: 1.41, 1.00–1.99) when BDNF was 1.5 SD lower than the mean value standardized for sex and age, education level, diabetes, and current smoking.Conclusion: Low serum BDNF was associated with lower cognitive test scores and MCI. Future prospective studies should establish the discriminative value of serum BDNF for the risk of MCI

An Enhanced Robotic Library System for an Off-Site Shelving Facility

This paper describes our continued work of a unique robotics project, Comprehensive Access to Printed Materials (CAPM), within the context of libraries. As libraries provide a growing array of digital library services and resources, they continue to acquire large quantities of printed material. This combined pressure of providing electronic and print-based resources and services has led to severe space constraints for many libraries, especially academic research libraries. Consequently, many libraries have built or plan to build off-site shelving facilities to accommodate printed materials. However, given that these locations are not usually within walking distance of the main library, access to these materials, specifically the ability to browse, is greatly reduced. Libraries with such facilities offer extensive physical delivery options from these facilities, sometimes offering multiple deliveries per day. Even with such delivery options, the ability to browse in real-time remains absent. The goal of the CAPM Project is to build a robotic, on-demand and batch scanning system that will allow for real-time browsing of printed materials through a web interface. We envisage the system will work as follows: an end user will identify that a monograph is located in an off-site facility. The user will engage the CAPM system that, in turn, will initiate a robot that will retrieve the requested item. The robot will deliver this item to another robotic system that will open the item and turn the pages automatically