Unreinforced Concrete Masonry Walls Strengthened with CFRP Sheets and Strips under Pendulum Impact

Impact tests using drop-weight pendulum on nine 1.2-m-high full-scale concrete masonry block walls were conducted to investigate the out-of-plane impact behavior of unreinforced masonry (URM) walls externally strengthened with carbon-fiber-reinforced polymer (CFRP) composites. Three strengthening schemes on one side of the wall were studied: continuous unidirectional and continuous woven sheets, discrete strips in a vertical pattern, and discrete strips in orthogonal and diagonal patterns. All walls were vertically positioned resting on a knife-edge support with one face leaning against two steel rollers close to the upper and lower edges of the wall. The impact load was applied at the wall center through a drop-weight pendulum impact tester with various drop heights. Test results revealed that using composite laminates or strips could significantly improve the impact performance of URM walls. The wall strengthened with continuous woven sheets performed better than the one with unidirectional sheet. With the same amount of fiber-reinforced polymer strip material, the wall with narrower but more closely spaced strips performed slightly better than the one with wider strips.     

Reproducibility of three different methods of measuring baroreflex sensitivity in normal subjects

1. Baroreflex sensitivity is a useful tool for investigating cardiovascular reflexes in a number of clinical settings. Several different methods of measuring baroreflex sensitivity are available. In order to determine a clinically useful non-invasive method of measuring baroreflex sensitivity we compared two methods (spectral analysis and the Valsalva manoeuvre) with regard to reproducibility, agreement with a standard invasive method (phenylephrine infusion) and failure rate.2.Twenty-six healthy subjects aged 22 to 63 years attended on three separate occasions for measurement of baroreflex sensitivity using the different methods. The effect of a recent head-up tilt on baroreflex sensitivity was measured.3. Reproducibility was best for the low-frequency component of the spectral method [coefficient of variation 25.0% (range 3.5-42.4%)] and worst for the Valsalva method [coefficient of variation 29.3% (range 13.8-93.1%)]. Both non-invasive methods overestimated values compared with the phenylephrine method [bias of low-frequency component of the spectral method, 1.17 (0.38-3.6); bias of the Valsalva method, 1.13 (0.19-6.7)]. The high-frequency component of the spectral method did not agree with the phenylephrine method.4. The spectral analysis method had the fewest failures (seven subjects with a failure on at least one occasion), and the phenylephrine method the most (16 subjects with a failure on at least one occasion). A short head-up tilt did not affect the subsequent non-invasive measurement of baroreflex sensitivity.5. It was concluded that the low-frequency component of the spectral method was the most clinically useful non-invasive measurement of baroreflex sensitivity.     

Evaluation procedures for lightning impulse parameters in case ofwaveforms with oscillations and/or an overshoot

Definitions of standards IEC 60 and IEEE Std 4 are insufficient for the evaluation of lightning impulse parameters of waveforms with oscillations and/or overshoot. This has brought about different interpretations in the estimation of these parameters, especially when using digital recorders. Large discrepancies have resulted from the different interpretations. The working group 33.03 of CIGRE has collected various opinions about this problem. These are presented, analysed and discussed in this paper. Different ways of determining mean curves of impulses with oscillations and/or overshoot are proposed. In addition, different alternatives for the definitions of overshoot amplitude and duration are suggested for impulses with overshoot. The problems and alternative solutions are discussed in the light of analyzing three impulses of the IEC Test Data Generator. This illustrates clearly the need to change the above mentioned standards. Simple, easily applicable, reproducible and technically justified definitions are required in order to take advantage of the accuracy and facilities of digital recorders in impulse measurements. This paper offers the basis for further discussion on the subject before WG 33.03 of CIGRE makes its final proposal. Further studies with practical test impulses are still needed     

The structure of SiC-reinforced Mg casting alloys

The nature of the interface and interfacial reaction products formed between SiC particles and magnesium has been studied in two SiC_p-reinforced magnesium casting alloys, ZC63 and ZE63. In ZC63, a thin amorphous film was observed at the interface of the SiC particles. Energy-dispersive X-ray and electron energy-loss spectroscopy methods were used to characterize the films. They were found to contain Si, O and Mg, with the Si tetrahedrally coordinated to the O. The alloy ZE63 contains Zr and mischmetal (Ce, La, Nd, Pr), all of which are strong oxide formers. In the as-cast state, patches or continuous fine-grained oxide films were found at the interface of the SiC reinforcing phase in this alloy. Electron diffraction was used to identify these oxides as the tetragonal form of ZrO₂ and cubic CeO₂.     

Stereoscopic head-mounted display incorporated into microsurgical procedures: technical note

OBJECTIVE: We have previously evaluated video technologies that have allowed for the use of electronic imaging during microneurosurgical and endoscopic procedures. This stereoscopic camera set and monitor/recording system allows for the use of stereoscopic images during surgery by the primary surgical assistant and ancillary personnel. It also allows for stereoscopic recording and playback using a wide video home system format. We describe a novel prototype of a head-mounted display (HMD) that allows the surgical team to simultaneously visualize the surgical field stereoscopically and includes picture-in-picture, voice control, and stereoscopic recording capabilities. INSTRUMENTATION: A stereoscopic HMD with 640 x 480 (video graphics array) pixel resolution and the ability to display 24-bit images has been designed. This device weighs 900 g. It is interfaceable with common video display formats. RESULTS: This stereoscopic HMD is being evaluated in a prospective multicenter trial of open microsurgical and endoscopic minimally invasive procedures. In our experience to date, there have been no equipment failures or complications attributable to the use of the display system. The equipment was well accepted by users who reported significant benefits in visualization. CONCLUSION: The use of a stereoscopic HMD may result in improved efficiency and safety in both endoscopic and open microsurgical procedures. We have verified that the HMD is comfortable during the course of a surgical procedure, is reliable, and allows for accessibility to the operative field with an excellent field of view and three-dimensional perception. Positioning and dexterity within the operative field are also enhanced. Additional uses relate to surgical training, multimodal information display, and operative rehearsals.     

Equipping Undergraduates for the Graduate School Process

The objective of this paper is to document a successful seminar series developed and used at Purdue University which educates undergraduates about graduate school and equips them to successfully move through the application and financial aid processes. The seminars are designed for all engineering disciplines. The series consists of four seminars given during a two-week period every fall and spring semester. The four seminars are “Graduate Study in Engineering: To Go or Not to Go, That is the Question,” “Helping Engineers Prepare for the General Graduate Record Exam (GRE),” “Approach and Helpful Hints on the GRE Engineering Exam,” and “Strategies for Applying to National Fellowship Programs.” The semester attendance for the four seminars collectively ranges from 150 to 250 students per semester. Data from student evaluations indicate that student knowledge about the graduate school process increases between 66%-164% for the four seminars. An alternative format for a single seminar highlighting all four topics has also been implemented.     

Digital techniques in HV tests-summary of 1989 panel session

A panel session on digital techniques in high-voltage (HV) tests was held at the IEEE PES Summer Meeting in Long Beach, CA, in 1989. The authors present an outline of the panel session and list pertinent reference material. This panel addressed the question of how signal processing can be used to enhance high voltage tests and extract more information from them. The first part dealt with the evaluation of digitizers and records and the second with the application of digitizers to industrial testing     

The process of sex-role integration in psychotherapy: Contributions from a training experience.

Feminist therapists face contradictions between avoiding abuse of power and accepting legitimate authority; between affective sharing and the use of intimacy to circumvent relational conflicts; between their feminist beliefs and internalized, unconscious sex-role norms; and between their collaborative values and the hierarchical nature of their discipline and of psychotherapy. These contradictions are most accessible to therapists-in-training for whom supervision can heighten an awareness of the interplay between personal influences and technical requirements. Two developmental models are provided for delineating feminine therapists' evolving use of these contradictions in their formulations of client dynamics and in the therapy relationship. Case examples from therapists in training translate these models into specifics of clinical practice. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Calculating the parameters of full lightning impulses usingmodel-based curve fitting

A brief review is presented of the techniques used for the evaluation of the parameters of high voltage impulses and the problems encountered. The determination of the best smooth curve through oscillations on a high voltage impulse is the major problem limiting the automatic processing of digital records of impulses. Nonlinear regression, based on simple models, is applied to the analysis of simulated and experimental data of full lightning impulses. Results of model fitting to four different groups of impulses are presented and compared with some other methods. Plans for the extension of this work are outlined     

Felling of individual freestanding nanoobjects using focused-ion-beam milling for investigations of structural and transport properties

We report that, to enable studies of their compositional, structural and electrical properties, freestanding individual nanoobjects can be selectively felled in a controllable way by the technique of low-current focused-ion-beam (FIB) milling with the ion beam at a chosen angle of incidence to the nanoobject. To demonstrate the suitability of the technique, we report results for zigzag/straight tungsten nanowires grown vertically on support substrates and then felled for characterization. We also describe a systematic investigation of the effect of the experimental geometry and parameters on the felling process and on the induced wire-bending phenomenon. The method of felling freestanding nanoobjects using FIB is an advantageous new technique enabling investigations of the properties of selected individual nanoobjects.