Influence of harmonics on power distribution system protection

The effects of nonsinusoidal voltages and currents on the performance of static underfrequency and overcurrent relays are experimentally studied. The tests were conducted in such a way that the frequency, amplitude and phase shift of individual harmonics could be adjusted in a controlled manner by using a waveform generator with a phase-locking circuit. The relationship between the harmonic currents and voltages was modeled in terms of the power system impedance within residential distribution systems. It was found that for harmonic voltage and current amplitudes (as they occur in distribution systems), underfrequency relays and the time delay operation of overcurrent relays show a marked deterioration in performance. The instantaneous operating characteristics of overcurrent relays, however, are hardly affected by the presence of harmonic currents     

Parental criticism and treatment outcome in adolescents hospitalized for severe, chronic asthma

This pilot study investigated the relationship between parental criticism and medical treatment outcome across an inpatient hospitalization in 19 adolescents with severe, chronic asthma. Parental criticism toward their asthmatic adolescent was assessed using the Five Minute Speech Sample technique (FMSS) at the beginning of the adolescent's inpatient stay at a national asthma referral center. Those adolescents whose parents were rated as high in criticism on the FMSS were found to have greater improvement in their overall asthma severity, greater reduction in their steroid medication dose, and shorter lengths of stay in the hospital than those whose parents were rated as low in criticism. The adolescents whose parents were rated as high in criticism also showed lower compliance with their prescribed theophylline and oral steroid medication at admission than the low criticism group. These findings do not appear to be due to misdiagnosis secondary to the presence of vocal cord dysfunction or to the allergy status of the children. Clinical implications and possible causal mechanisms underlying these findings are discussed.     

Design and control of a manipulator for tetraplegics

The design of a manipulator for tetraplegics was started with general considerations on the conditions under which such a system could serve as a substitute for the lost functions of upper extremities. The results of these considerations can be summarised in the following statements: The information flow from the tetraplegic as a disabled operator is small and merely sufficient to control a simple manipulator. Dexterity and versatility of this manipulator will be small, too. Only if the structure of the environment will be adapted to the functional capability of the system disabled operator/manipulator purposeful actions can be expected. The final goal of the design is the installation of working places where various severely disabled persons can be occupied with different kinds of desk work. As the interface between the disabled operator and the manipulator a control stick was chosen which can be moved into three directions. The manipulator was designed as an articulated arm with 6 degrees-of-freedom, 3 for the positioning have been realised in a prototype and 3 in the prehension device which is still in construction. Rate control was considered the most advantageous form of control for the disabled operator. Control facilitations as end point control, and the automatic control of the prehension axis have been included into the control unit. A computer based learning system which evaluates mean values of the control input signal is in preparation. Several directions for the implementation of an adapted environment have been worked out. They have been applied to design an adapted working room where tetraplegics can do desk work.     

Identification of harmless and pathogenic algae of the genus Prototheca by MALDI-MS

The only plants infectious for mammals, green algae from the genus Prototheca, are often overseen or mistaken for yeast in clinical diagnosis. To improve this diagnostical gap, a method was developed for fast and reliable identification of Prototheca. A collection of all currently recognized Prototheca species, most represented by several strains, were submitted to a simple extraction by 70% formic acid and ACN; the extracts were analyzed by means of MALDI-MS. Most of the peaks were found in the range from 4 to 20 kDa and showed a high reproducibility, not in absolute intensities, but in their peak pattern. The selection of measured peaks is mostly due to the technique of ionization in MALDI-MS, because proteins in the range up to 200 kDa were detected using gel electrophoresis. Some of the proteins were identified by peptide mass fingerprinting and MS² analysis and turned out to be ribosomal proteins or other highly abundant proteins such as ubiquitin. For the preparation of a heatmap, the intensities of the peaks were plotted and a cluster analysis was performed. From the peak-lists, a principal component analysis was conducted and a dendrogram was built. This dendrogram, based on MALDI spectra, was in fairly good agreement with a dendrogram based on sequence information from 18S DNA. As a result, pathogenic and nonpathogenic species from the genus Prototheca can be identified, with possible consequences for clinical diagnostics by MALDI-typing.     

OH absorption spectroscopy in a flame using spatial heterodyne spectroscopy

We demonstrate measurements of OH absorption spectra in the post-flame zone of a McKenna burner using spatial heterodyne spectroscopy (SHS). SHS permits high-resolution, high-throughput measurements. In this case the spectra span approximately 308-310 nm with a resolution of 0.03 nm, even though an extended source (extent of approximately 2x10(-7) m(2) rad(2)) was used. The high spectral resolution is important for interpreting spectra when multiple absorbers are present for inferring accurate gas temperatures from measured spectra and for monitoring weak absorbers. The present measurement paves the way for absorption spectroscopy by SHS in practical combustion devices, such as reciprocating and gas-turbine engines.     

基于大比尺模型试验的连续配筋混凝土路面开裂研究

为控制连续配筋混凝土路面（CRCP）的横向裂缝,修建大比尺模型-连续配筋混凝土梁（CRCB）,分析混凝土材料、配筋率、纤维及横向预切缝对CRCP开裂的影响. 构建解析模型推导横向裂缝间距和宽度的计算表达式,理论量化不同设计参数对CRCP横向裂缝特征的影响. 结果表明：解析结果与现场勘测数据吻合,说明解析法切实可行;横向裂缝随着试验梁龄期增长而发展,且于19个月后趋于稳定;配筋率对裂缝间距和宽度影响较大,采用筋径为22.23 mm（#7号钢筋）的试验梁,其裂缝间距和宽度比采用筋径为19.05 mm（#6号钢筋）的试验梁降低了17%左右;采用轻质混凝土可增大裂缝间距、减小裂缝宽度,为控制冲断提供可能;加入纤维和设置横向预切缝可增大裂缝间距、减小裂缝宽度.     

Finite element analysis of a concrete slab under various non-uniform support conditions

A two-dimensional finite element program was utilised to study the effects of a non-uniform subgrade support on the tensile stresses in a concrete slab. A total of 12 subgrade support conditions were created including uniform and non-uniform support. The modulus of subgrade reaction (k-value) for different support areas was arbitrarily assigned either a soft (50 psi/in., 13.5 MPa/m) or stiff (500 psi/in., 135 MPa/m) value. Three axle types (single, tandem and steer-drive), three linear temperature differentials (none, negative and positive), two loading paths (edge and wheel path) and multiple longitudinal wheel positions were considered in the analysis. The theoretical analyses showed that several non-uniform subgrade support cases had a profound impact on the peak tensile stresses in a slab. In particular, a stiff subgrade with soft edges and a subgrade with randomly assigned soft and stiff locations significantly increased the peak tensile stresses relative to a uniformly soft support condition by at least 30%.     

Longitudinal Cracking Distress on Continuously Reinforced Concrete Pavements in Illinois

The Illinois Department of Transportation (IDOT) initiated a failure investigation to determine the distress mechanisms causing premature longitudinal cracking on continuously reinforced concrete pavements (CRCP) on several Illinois interstates. The longitudinal cracking approximately followed the embedded reinforcement steel and occurred in both the driving and passing lanes. In this paper, the results from field visual surveys, coring, and petrographic analyses are reported along with a review of archival construction and material records of the distressed CRCP sections. A laboratory forensic study was also performed on several field extracted slabs. The results of the field and laboratory investigation show the cracking was not initiated by steel corrosion, deleterious reactions in the concrete materials, or an inadequate structural design. Rather, the cracking is related to settlement of the steel bars in the concrete. Settlement cracking is conventionally thought to occur only in concrete slabs and decks with plastic (high slump) concrete and small values of bar cover depth, while the studied CRCP sections have large values of cover depth and were cast with stiff (low slump) concrete. The settlement was likely caused by the relative settlement of heavy steel bars (22?mm diameter) within the lower density concrete during the original CRCP construction. The technique of placing the steel bars in the fresh concrete (called tube-feeding) further contributed to the development of this distress, and this practice is no longer employed by IDOT.     

Fermentation of glucose and starch particles using an inexpensive medium

BACKGROUND: In North America, compared with sugar, starch is a more economical raw material to produce ethanol. Recently low temperature processing of starch granules directly to ethanol has been commercialized. With a view to minimizing process costs while maintaining a satisfactory ethanol yield, an inexpensive medium that does not require the addition of commercial α‐amylase has been developed for low temperature, direct fermentation of starch particles. RESULTS: Compared with an expensive medium that contained both yeast extract and α‐amylase, the inexpensive medium resulted in identical and 10% higher ethanol yields using glucose and starch granules as the raw substrates, respectively, but required longer processing times. Based on the different ingredient prices for expensive and inexpensive media, the operating cost to produce 10 million litres per year of ethanol utilizing simultaneous raw starch hydrolysis and fermentation is reduced over $ 2 million (Cdn) per year when using inexpensive medium. CONCLUSION: The new inexpensive medium and simultaneous raw starch hydrolysis and fermentation is considered the best strategy to produce ethanol directly from starch particles in North America. Copyright © 2009 Society of Chemical Industry     

Antioxidant activity of Annona crassiflora: Characterization of major components by electrospray ionization mass spectrometry

The polar components of Annona crassiflora pulp, peel and seeds ethanolic extracts were investigated by direct infusion electrospray ionization mass spectrometry (ESI-MS) both in the negative ion mode. Characteristic ESI mass spectra with many diagnostic ions were obtained for the extracts, serving for fast and reliable information. The technique provided information of component structures revealing the presence of important bioactive components widely reported as potent antioxidants such as ascorbic acid, caffeic acid, quinic acid, ferulic acid, xanthoxylin, rutin, caffeoyltartaric acid, caffeoyl glucose and [quercetin+hexose+pentose−H]⁻¹ This is the first report on the composition by ESI-MS of araticum peel and seed ethanolic extracts demonstrating excellent antioxidant activity.