亚利桑那州立大学沃尔特·克朗凯特新闻与大众传播学院

为了振兴凤凰城市中心,亚利桑那州为亚利桑那州立大学的一个新建项目举办了几次跨越"毕业领奖台"的优秀设计.楼高6层,20,903m<'2>(295,000平方英尺)的沃尔特·克朗凯特新闻与大众传播学院建筑是其中快速设计、各方协力实施的典范.该建筑由建筑师Ehrlich、HDR建筑公司和和总承包商SUNDT建设公司通力合作,创造了在二十二个月内完成设计并交付使用的记录.     

一种新颖的双桥矩阵变换器控制策略

矩阵变换器是一种AC/AC变换器,它具有正弦输入电流、正弦输出电压、能量双向流动及体积小的优点,但存在着控制方法复杂,开关器件和保护元器件太多的问题.近年来提出的双桥矩阵变换器具有矩阵变换器的优点,同时其控制方法更简单,所用开关元件数目更少.论述了双桥矩阵变换器的原理,讨论了变换器的PWM控制策略以及基于线电压符号的换流方法,提出了整流级、逆变级单独控制,整流级开关频率为10kHz、逆变级开关频率为2kHz的新颖双桥矩阵变换器方案,给出了仿真和实验结果.     

Knight Mine reclamation: A study of revegetation difficulties in a semi-arid environment

ABSTRACT

An analysis of the difficulties associated with the re-establishment of reclamation vegetation on a dry mine site in southern Utah, U.S.A. is presented. Precipitation amounts, seed mix, seed bed preparation techniques, and soil properties all appeared to be adequate for vegetation establishment at the site. However, failure of repeated revegetation efforts in a redisturbed area of the mine site may have been due to higher soil salinity levels in the area, which may Have given Kochia scoparia an initial competitive advantage. Lack of soil moisture and allelopalhic effects due to the dense carpet of Kochia may have also contributed to the continued lack of revegetation success.     

On the Mechanism of Lubrication by Tricresylphosphate (TCP)—The Coefficient of Friction as a Function of Temperature for TCP on M-50 Steel

A pin-on-disk tribometer was used to study the coefficient of friction as a function of temperature for tricresylphosphate (TCP) on CVM M-50 tool steel under the following conditions: TCP was present in a liquid reservoir (bulk lubrication), and TCP was applied as a liquid layer directly to the disk (limited lubrication). Under limited lubrication conditions, experiments were performed in dry (< 100 ppm H₂O) air, dry (< 20 ppm H₂O) nitrogen, dry nitrogen with the disks heated to 700°C, then cooled to room temperature before the TCP was applied and the measurements made (preheated disks), and moist nitrogen using preheated disks. The coefficient of friction decreased at a characteristic temperature, T_r T_r values observed were: 265°C for bulk lubrication conditions in dry air, 225°C for limited lubrication conditions in dry air, and 215°C for limited lubrication conditions in dry nitrogen. The use of preheated disks produced a sharp failure temperature at 218°C which was taken as the temperature about which the behavior of TCP should be judged. X-ray photoelectron spectroscopy confirmed the presence of phosphate on the surface of TCP-lubricated iron pins. Depth profile studies support the suggestion that a chemical reaction occurs between the TCP and the metal surface at T_r.     

Development of an indoor rowing machine with manual FES controller for total body exercise in paraplegia

Concept 2 indoor rowing machine (Concept 2 Inc., USA) was modified for functional electrical stimulation (FES) rowing exercise in paraplegia. A new seating system provides trunk stability and constrains the leg motion to the sagittal plane. A 4-channel electrical stimulator activates the quadriceps and hamstrings in Drive and Recovery phases of the rowing cycle, respectively. Two force-sensing resistors (FSR) on the handle measure the thumb press as the command signal to the electrical stimulator. Optical encoders measure the positions of the seat and handle during rowing. To synchronize the voluntarily controlled upper body movement with the FES controlled leg movement, a novel manual control system was developed. It uses the voluntary thumb presses to control the timing of the stimulation to the paralyzed leg muscles. The manual control system was intuitive and easy to learn and resulted in well-coordinated rowing. Evaluation of the modified rower by paraplegic volunteers showed that it is effective, safe, and affordable exercise alternative for paraplegics.     

Using statistical process control charts for the continual improvement of asthma care

BACKGROUND: Home monitoring of lung function using simple, inexpensive tools to measure peak expiratory flow rate (PEFR) has been possible since the 1970s. Yet although current national and international guidelines recommend monitoring of PEFRs via traditional run charts, their use by both patients and physicians remains low. The role of statistical process control (SPC) theory and charts in the serial monitoring of lung function at home were explored and applied to the direct care of patients with asthma. The method represents an integration of collective professional and improvement knowledge with the related disciplines of continual improvement, SPC, system thinking/system dynamics, paradigms, and the learning community/organization. CASE STUDIES: Use of PEFR control charts for four patients cared for at the Asthma-Allergy Clinic and Research Center (Shreveport, La) is described. The key to good asthma control is the ability to optimize lung function by reducing the variation between serial lung function measurements and thereby generate a safe range of function. Knowledge of the type of variation (special cause or common cause) in the system helps in focusing clinical decision making. Case 4, an 11-year-old boy, for example, shows how control charts were used to learn the effects of a new inhaled corticosteroid. Comparison of the last 14 days of baseline and the last 14 days of open label use of the inhaled corticosteroid showed an obvious improvement in actual PEFR values--which a run chart or comparison of means would have easily demonstrated. The control chart showed that this child's care process at baseline was functionally at risk for severe asthma (46% personal best) and that the effect of the new medication not only elevated the mean function but shifted the range of function from 46%-72% personal best to 78%-102% personal best. At this new range of function the patient's system of care was not capable of delivering values that are at risk for severe asthma. Unless the range of function the change in care is capable of producing is specifically quantitated, misinterpretation of improvement data can occur. DISCUSSION: Developing the concept of the PEFR control chart involved examining and challenging traditional mental models for monitoring PEFR at home in the care of asthma, acquiring a better understanding of the workings of dynamic systems and with system thinking, and sharing what was learned with patients and seeking their input. CONCLUSIONS: The PEFR control chart employs an interesting statistical platform that enables the integration of knowledge of serial measurements and knowledge of the variation between those measurements into a tool with which to better assess the asthma care process being followed. This tool provides clinical insights, practical knowledge, and opportunities unavailable to patients and physicians via traditional PEFR charting.     

Seroprevalence survey of Egyptian tourism workers for hepatitis B virus, hepatitis C virus, human immunodeficiency virus, and Treponema pallidum infections: association of hepatitis C virus infections with specific regions of Egypt

Blood samples from 740 Egyptian Nationals working in the tourism industry at two sites in the South Sinai governorate were screened for markers of infection with hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), and Treponema pallidum. Study subjects included 467 individuals from a rural seashore tourist village and 273 persons at two hotels in a well-established resort town. Subjects' ages ranged from 15 to 70 years; 99.3% were male. The prevalence of serologic markers for currently asymptomatic or past HBV infection alone was 20.7% (n = 153), of markers for past or chronic HCV infection alone was 7.4% (n = 55), and of markers for both HBV and HCV was 6.9% (n = 51). Of the 204 individuals positive for anti-HBV core antibody, 12 (5.9%) were also positive for hepatitis B surface antigen. Two individuals (0.3%) had a serologic market suggestive of an active syphilitic infection. No subject was found to be HIV-seropositive. History of prior injections and number of injections were associated with infection with HCV. Primary residence in the Nile delta and valley areas where schistosomiasis is highly endemic, was also a statistically significant risk factor for HCV, but not HBV infection.