bluuebunny/crossref_metadata_2025 huggingface dataset:
Systolic Blood Pressure Response During Exercise Stress Testing: The Henry Ford ExercIse Testing (FIT) Project
Authors: O'Neal Wesley T. , Qureshi Waqas T. , Blaha Michael J. , Keteyian Steven J. , Brawner Clinton A. , Al‐Mallah Mouaz H.
Published: May 2015

Background

The prognostic significance of modest elevations in exercise systolic blood pressure response has not been extensively examined.

Methods and Results

We examined the association between systolic blood pressure response and all‐cause death and incident myocardial infarction (MI) in 44 089 (mean age 53±13 years, 45% female, 26% black) patients who underwent exercise treadmill stress testing from the Henry Ford ExercIse Testing (FIT) Project (1991–2010). Exercise systolic blood pressure response was examined as a categorical variable (>20 mm Hg: referent; 1 to 20 mm Hg, and ≤0 mm Hg) and per 1 SD decrease. Cox regression was used to compute hazard ratios (HR) and 95% CI for the association between systolic blood pressure response and all‐cause death and incident MI. Over a median follow‐up of 10 years, a total of 4782 (11%) deaths occurred and over 5.2 years, a total of 1188 (2.7%) MIs occurred. In a Cox regression analysis adjusted for demographics, physical fitness, and cardiovascular risk factors, an increased risk of death was observed with decreasing systolic blood pressure response (>20 mm Hg: HR=1.0, referent; 1 to 20 mm Hg: HR=1.13, 95% CI=1.05, 1.22; ≤0 mm Hg: HR=1.21, 95% CI=1.09, 1.34). A trend for increased MI risk was observed (>20 mm Hg: HR=1.0, referent; 1 to 20 mm Hg: HR=1.09, 95% CI=0.93, 1.27; ≤0 mm Hg: HR=1.19, 95% CI=0.95, 1.50). Decreases in systolic blood pressure response per 1 SD were associated with an increased risk for all‐cause death (HR=1.08, 95% CI=1.05, 1.11) and incident MI (HR=1.09, 95% CI=1.03, 1.16).

Conclusions

Our results suggest that modest increases in exercise systolic blood pressure response are associated with adverse outcomes.
Relative Influence of Capillary Index Score, Revascularization, and Time on Stroke Outcomes From the Interventional Management of Stroke III Trial
Authors: Al-Ali Firas , Elias John J. , Tomsick Thomas A. , Liebeskind David S. , Broderick Joseph P.
Published: May 2015

Background and Purpose—

Until recently, acute ischemic stroke (AIS) trials have failed to show a benefit of endovascular therapy compared with standard therapy, leading some authors to recommend decreasing the time from ictus to revascularization to improve outcomes. We hypothesize that improving patient selection using the capillary index score (CIS) may also be a useful strategy.

Methods—

CIS was calculated, blinded to outcome, from pretreatment diagnostic cerebral angiograms for 78 subjects in the Interventional Management of Stroke III database with internal carotid artery and middle cerebral artery trunk occlusion. The CIS was dichotomized into favorable (
f
CIS=2 or 3) and poor (
p
CIS=0 or 1). Outcomes were categorized based on the modified Rankin Scale score at 90 days (0–2 considered a good outcome). Modified thrombolysis in cerebral infarction score 2b or 3 was considered good revascularization. Multivariable logistic regression was performed to relate CIS, time from ictus to revascularization, modified thrombolysis in cerebral infarction score, and National Institue of Health Stroke Scale score to good outcomes.

Results—

Only CIS and modified thrombolysis in cerebral infarction scores were correlated with good outcomes (
P
<0.01). Patients with
f
CIS and good revascularization achieved 71% modified Rankin Scale ≤2, compared with 13% for patients with
p
CIS and good revascularization.

Conclusions—

In this subset of patients from the Interventional Management of Stroke III Trial, CIS and modified thrombolysis in cerebral infarction were strong predictors of outcome after endovascular reperfusion. Using the CIS to improve patient selection could be a powerful strategy to improve rate of good outcomes in endovascular therapy. A randomized trial is needed.

Clinical Trial Registration—

URL:
http://www.clinicaltrials.gov
. Unique identifier: NCT00359424.
Is Blood Pressure Control for Stroke Prevention the Correct Goal?
Authors: Howard George , Banach Maciej , Cushman Mary , Goff David C. , Howard Virginia J. , Lackland Daniel T. , McVay Jim , Meschia James F. , Muntner Paul , Oparil Suzanne , Rightmyer Melanie , Taylor Herman A.
Published: May 2015

Background and Purpose—

Although pharmacological treatment of hypertension has important health benefits, it does not capture the benefit of maintenance of ideal health through the prevention or delay of hypertension.

Methods—

A total of 26 875 black and white participants aged 45+ years were assessed and followed for incident stroke events. The association was assessed between incident stroke and: (1) systolic blood pressure (SBP)categorized as normal (<120 mm Hg), prehypertension (120–139 mm Hg), stage 1 hypertension (140–159 mm Hg), and stage 2 hypertension (160 mm Hg+), and (2) number of classes of antihypertensive medications, classified as none, 1, 2, or 3 or more.

Results—

During 6.3 years of follow-up, 823 stroke events occurred. Nearly half (46%) of the population were successfully treated (SBP<140 mm Hg) hypertensives. Within blood pressure strata, the risk of stroke increased with each additional class of required antihypertensive medication, with hazard ratio [HR], 1.33; 95% confidence interval, 1.16 to 1.52 for normotensive, HR, 1.15; 95% confidence interval, 1.05 to 1.26 for prehypertension, and HR, 1.22; 95% confidence interval, 1.06 to 1.39 for stage 1 hypertension. A successfully treated (SBP<120 mm Hg) hypertensive person on 3+ antihypertensive medication classes was at marginally higher stroke risk than a person with untreated stage 1 hypertension (HR, 2.48 versus HR=2.19; relative to those with SBP <120 on no antihypertensive medications).

Conclusions—

Maintaining the normotensive status solely through pharmacological treatment has a profound impact, as nearly half of this general population cohort were treated to guideline (SBP<140 mm Hg) but failed to return to risk levels similar to normotensive individuals. Even with successful treatment, there is a substantial potential gain by prevention or delay of hypertension.
Sharī‘a and State Law
Authors: Abbasi Muhammad Zubair
Published: May 2015

The growing numbers of Muslims in the West have ignited a debate about the compatibility of Sharī‘a with state law. The present article explores the issue from a historical perspective by providing a brief survey of Islamic legal history. It specifically focuses on the interaction of Sharī‘a with the English legal system in colonial India. The main argument of the article is that during its long history, Sharī‘a co-existed with the ruler’s law (siyāsa) and customary law (‘urf). It was formally incorporated into the structure of the state with the active participation of Muslim legal commentators, judges, lawyers, politicians, and the ‘ulamā’ in colonial India. The incorporation of Sharī‘a into the state law was facilitated through the transplantation of legislative and hierarchical judicial institutions, which provided venues for a legal discourse among various stakeholders. Historical evidence suggests the feasibility of incorporating Sharī‘a into state law in Western democratic countries.
The Role of Libraries in the Missionary Regions of Orinoquia
Authors: del Rey Fajardo S.J. José
Published: May 2015

Beginning in 1661, the Jesuits conducted missionary activity in the Orinoquia [the Orinoco delta]. Among the more significant challenges was the introduction of literacy to a people whose concepts of history and society were quite foreign to Spanish and Italian priests. Creating Christians would therefore entail creating a literate culture: the Jesuits began by learning local traditions and committing these to paper, and only then teaching the children of the region to read and write. While none of these teaching books survive, the missionary schools and houses kept libraries which included volumes on regional crafts and history, along with items the Jesuits considered useful or necessary: music, instruments, and books authored by members of the Society. The inhabitants of the Orinoco River watershed thus had access to European books as well as those in indigenous languages, both of which simultaneously supported and shaped life within the missions and reductions.
A checklist of woody Leguminosae in the South American Corridor of Dry Vegetation
Authors: Lima Jacira Rabelo , Tozzi Ana M.G.A , Mansano Vidal Freitas
Published: May 2015

A checklist for woody Leguminosae in the South American Corridor of Dry Vegetation was based on published data (286 floristic lists) and collections from nine herbaria. A total of 781 species (117 genera and 16 tribes) were found. The Chaco showed highest species richness, despite having the lowest taxonomic distinctness index (∆*). Data from herbaria formed a large contribution to the evaluation of the diversity of the vegetation studied. Each vegetation type has a considerable number of endemic species, demonstrating the importance of conserving all types of seasonally dry vegetation present in South America.
A taxonomic revision of the genus Xerodraba (Eudemeae, Brassicaceae)
Authors: Salariato Diego Leonel , Zuloaga Fernando O. , Al-Shehbaz Ihsan A.
Published: May 2015

Xerodraba is a South American genus distributed exclusively in the Andean-Patagonian region of southern Argentina and Chile. It is characterized by forming cushions with imbricate, scalelike leaves and solitary, terminal flowers. An updated taxonomic revision of the genus based on morphological analyses using both qualitative and quantitative characters is presented here. Xerodraba currently includes five species distributed in Argentina, of which two also grow in Chile. Xerodraba pectinata is reduced to synonymy of X. lycopodioydes, and X. pycnophylloides is treated as a subspecies of X. patagonica. The new combination X. patagonica subsp. pycnophylloides is proposed. Descriptions, keys to all taxa, updated geographical distributions, maps, and illustrations are provided.
A new species of Tovomita Aubl. (Clusiaceae) from the Brazilian Atlantic Forest
Authors: Marinho Lucas Cardoso , Fiaschi Pedro , Amorim André Márcio
Published: May 2015

Tovomita iaspidis, a new species from the Brazilian Atlantic Forest, is described, illustrated, and its morphological affinities with other species and its diagnostic characters are discussed. The new species is similar to Tovomita glazioviana, from which it can be distinguished by having greenish patent petals and larger and reddish pistillode in the staminate flowers. While T. glazioviana is found in the Atlantic Forest in the states of Bahia, Minas Gerais, and Rio de Janeiro, T. iaspidis is so far only known from two small remnant areas of montane forest in southern Bahia State, Brazil.
Taxonomic notes on the crab spider genera Stephanopoides and Isaloides (Araneae: Thomisidae: Stephanopinae)
Authors: TEIXEIRA RENATO AUGUSTO , BARROS BRUNO AUGUSTO REIS
Published: May 2015

According to current catalogues, two species are allocated to the genus Parastephanops F. O. Pickard-Cambridge, 1900. The examination of the type of Parastephanops cognatus (O. Pickard-Cambridge, 1892) (type-species of Parastephanops) has revealed the presence of a high cephalic region, legs with dark metatarsus and apex of tibia, and triangular epigynum with median ridge, all diagnostic features of Stephanopoides Keyserling, 1880. However, the female of P. echinatus (Banks, 1914) has a low cephalic region, a median ocular quadrangle longer than wide and a large atrium of the epigynum, which are diagnostic features of Isaloides F. O. Pickard-Cambridge, 1900. Thus, Parastephanops is synonymized with Stephanopoides and its two species, P. cognatus and P. echinatus, are redescribed, illustrated and assigned to Stephanopoides and Isaloides, respectively. We also propose that Pyresthesis berlandi Caporiacco, 1947 is a junior synonym of Stephanopoides simoni Keyserling, 1880 based on shape and arrangement of the epigynal plate, copulatory ducts and spermathecae.
A new species of Amanahyphes Salles & Molineri, 2006 (Ephemeroptera: Leptohyphidae) from Bahia, Brazil
Authors: MOLINERI CARLOS , LIMA LUCAS R. C. , KNAPP WILLIAM D. , DOCIO LOYANA
Published: May 2015

A new species of the previously monotypic genus Amanahyphes Salles & Molineri, 2006 is described based on the male imago, egg and nymph from the state of Bahia, Brazil. Characters and illustrations to distinguish Amanahyphes bahiensis sp. nov. from A. saguassu and all other species in Leptohyphidae are provided. Amanahyphes bahiensis sp. nov. is diagnosed as follows: in the male imago, forewing shaded slightly with brownish at basal third and penes basally fused, distally with diverging lobes, and with a short spine-like projection at midlength on lateral margin; in the nymph, femoral spines long, slender and acuminate, tarsal claws with 10–11 marginal denticles and 2+3 subapical submarginal denticles, gill formula 3/2/2/2. Geographic records of both species are amended and indicated on a map.
A Regression-Based Approach for Cool-Season Storm Surge Predictions along the New York–New Jersey Coast
Authors: Roberts Keith J. , Colle Brian A. , Georgas Nickitas , Munch Stephan B.
Published: May 2015

A multilinear regression (MLR) approach is developed to predict 3-hourly storm surge during the cool-season months (1 October–31 March 31) between 1979 and 2012 using two different atmospheric reanalysis datasets and water-level observations at three stations along the New York–New Jersey coast (Atlantic City, New Jersey; the Battery in New York City; and Montauk Point, New York). The predictors of the MLR are specified to represent prolonged surface wind stress and a surface sea level pressure minimum for a boxed region near each station. The regression underpredicts relatively large (≥95th percentile) storm maximum surge heights by 6.0%–38.0%. A bias-correction technique reduces the average mean absolute error by 10%–15% at the various stations for storm maximum surge predictions. Using the same forecast surface winds and pressures from the North American Mesoscale (NAM) model between October and March 2010–14, raw and bias-corrected surge predictions at the Battery are compared with raw output from a numerical hydrodynamic model’s [the Stevens Institute of Technology New York Harbor Observing and Prediction System (SIT-NYHOPS)] predictions. The accuracy of surge predictions between the SIT-NYHOPS output and bias-corrected MLR model at the Battery are similar for predictions that meet or exceed the 95th percentile of storm maximum surge heights.
Sea Surface Temperature Predictions in NCEP CFSv2 Using a Simple Ocean Initialization Scheme
Authors: Zhu Jieshun , Kumar Arun , Wang Hui , Huang Bohua
Published: May 2015

In contrast to operational climate predictions based on sophisticated ocean data assimilation schemes at the National Centers for Environmental Predictions (NCEP), this study applied a simple ocean initialization scheme to the NCEP latest seasonal prediction model, the Climate Forecast System, version 2 (CFSv2). In the scheme, sea surface temperature (SST) was the only observed information applied to derive ocean initial states. The physical basis for the method is that, through air–sea coupling, SST is capable of reproducing some observed features of ocean evolutions by forcing the atmospheric winds. SST predictions based on the scheme are compared against hindcasts from the National (lately North American) Multimodel Ensemble (NMME) project.

It was found that due to substantial biases in the tropical eastern Pacific in the ocean initial conditions produced by SST assimilation, ENSO SST predictions were not as good as those with sophisticated initialization schemes (e.g., hindcasts in the NMME project). However, in other basins, SST predictions based on a simple ocean initialization procedure were not worse (sometimes even better) than those with sophisticated initialization schemes. These comparisons indicate that it was helpful that subsurface ocean information be assimilated to improve the tropical Pacific SST predictions, while SST-based ocean assimilation was an effective way to enhance SST prediction capability in other ocean basins. By examining multimodel ensembles with the simple scheme-based hindcasts either included or excluded in NMME, it is also suggested that including the hindcast would generally benefit multimodel ensemble forecasts. In addition, possible ways to further improve ENSO SST predictions with the simple initialization scheme are also discussed.
Evaluating Hail Damage Using Property Insurance Claims Data
Authors: Brown Tanya M. , Pogorzelski William H. , Giammanco Ian M.
Published: May 2015

A series of thunderstorms on 24 May 2011 produced significant hail in the Dallas–Fort Worth (DFW) metroplex, resulting in an estimated $876.8 million (U.S. dollars) in insured losses to property and automobiles, according to the Texas Department of Insurance. Insurance claims and policy-in-force data were obtained from five insurance companies for more than 67 000 residential properties located in 20 ZIP codes. The methodology for selecting the 20 ZIP codes is described. This study evaluates roofing material type with regard to resiliency to hailstone impacts and relative damage costs associated with roofing systems versus wall systems. A comparison of Weather Surveillance Radar-1988 Doppler (WSR-88D) radar-estimated hail sizes and damage levels seen in the claims data is made. Recommendations for improved data collection and quality of insurance claims data, as well as guidance for future property insurance claims studies, are summarized. Studies such as these allow insurance underwriters and claims adjusters to better evaluate the relative performance and vulnerability of various roofing systems and other building components as a function of hail size. They also highlight the abilities and limitations of utilizing radar horizontal reflectivity-based hail sizes, local storm reports, and Storm Data for claims processing. Large studies of this kind may be able to provide guidance to consumers, designers, and contractors concerning building product selections for improved resiliency to hailstorms, and give a glimpse into how product performance varies with storm exposure. Reducing hail losses would reduce the financial burden on property owners and insurers and reduce the amount of building materials being disposed of after storms.
Spine Posture and Discomfort During Prolonged Simulated Driving With Self-Selected Lumbar Support Prominence
Authors: De Carvalho Diana E. , Callaghan Jack P.
Published: May 2015

Objective:

We examined magnitude preference, subjective discomfort, and spine posture during prolonged simulated driving with a self-selected amount of lumbar support.

Background:

The general use of lumbar supports has been associated with decreased reports of low-back pain during driving exposures; however, minimal data exist regarding occupant magnitude preference.

Method:

Participants chose between five discrete levels of lumbar support (0–4 cm). Time-varying postural and discomfort responses were then monitored throughout 2 hr of simulated driving.

Results:

There were no significant effects of gender or time on posture. Women preferred larger amounts of support than men (3.25 cm ± 0.71 and 2.56 cm ± 0.88, respectively, p = .048). All participants exhibited significant increases ( p = .003) in pelvic discomfort throughout the 2-hr trial regardless of the level of support chosen. Discomfort related to various aspects of the lumbar support increased significantly over time. Retrospectively, no participants desired a setting beyond 4 cm, and the majority of respondents indicate had they been able to change their initial selection, they would choose a setting between 2 and 3 cm.

Conclusion:

The results suggest that occupants would prefer increasing the excursion capability of automobile lumbar supports beyond 2 cm.

Application:

Excursion capability and adjustability of automobile lumbar supports are important features to better meet end-user preference and to reducing lumbar flexion in sitting.
Teaching and Assessing 200 Second-Year Electrical Engineering Students
Authors: Donaldson G. W.
Published: May 2015

The central problem in teaching large numbers of students is to keep close personal contact between students and staff and also to have an efficient organization. Presented here is one solution to questions of motivation, participation and assessment, but each lecturer should be free to find his own.
Graphical Solution of Some Simple Impedance Networks
Authors: Tai C.-T.
Published: May 2015

The graphical solutions to some simple impedance networks, including L, T, and π configurations are presented here together with the analytic derivations. These graphs are helpful in visualizing the values of the circuit elements in designing impedance matching networks. Based upon these circuits, the constructions depend primarily on conversions between parallel and series circuits that are accomplished by means of straight lines instead of semi-circles as described previously by McNally and Keen.
A Simplified Three-Dimensional Analysis of a Solid Rotor Induction Machine with Finite Current Sheet and Finite Stator Permeability
Authors: Basu S. , Mukhopadhyaya P.
Published: May 2015

The paper presents a method of analysis of a solid rotor induction machine, in which both finite stator permeability and finite thickness of current sheet, not considered so far, have been incorporated. To take the finite axial length of the machine into account, a three-dimensional model of a machine is considered and the analysis is made in rectangular co-ordinates. The method, unlike the previous ones, indicates an easier way of studying machine characteristics, even though it is more rigorous in nature.
An Indirect Method for Solving Non-Linear Optimal Control Problems in Power Systems-Part 1
Authors: Malik O. P. , Mukhopadhyay B. K. , Subramaniam P.
Published: May 2015

This paper describes the application of quasilinearization algorithm and its various modifications to solve the non-linear optimal control problems in power systems. Results obtained by this indirect numerical technique are compared to those obtained by other, direct methods. It is shown that a proposed hybrid approach, in conjunction with the continuation method, can be considered as an effective iterative procedure for most practical problems in power systems.
On the Effects of Surge Absorbers-Part II. Numerical Results
Authors: Sakr M. M. , Mansour E. A. A. , Girgis R. S.
Published: May 2015

The results are given of a numerical evaluation of the equations corresponding to the output voltage from a surge absorber, as derived in Part I. Curves have been plotted to show how the constants of the absorber, and the capacitance of the capacitor simulating the transformer, affect the wave form of the incident surge.

As it is the main function of the surge absorber to reduce ‘the voltages induced in the apparatus connected to it, a comparison has been made between the stresses produced in a transformer due to a unit step surge with and without the presence of the absorber.
Transient Field Analysis of a Solid Steel Block
Authors: Bansal V. K. , Basu S. , Mukhopadhyay P.
Published: May 2015

The paper presents an elegant method of analysis for studying the transient response of a solid block of steel subjected to either unit impulse input or unit step function input. In this analysis, B—H relationship is assumed to be linear. The differential equations involving the field quantities for the two-dimensional and three-dimensional representation of the mathematical model are reduced to a simple form with the help of suitable transformation.
An Undergraduate Course in Switchgear and Protection
Authors: Zorbas N.
Published: May 2015

The paper describes an undergraduate course in Switchgear and Protection offered to final year electrical power engineering students at the Western Australian Institute of Technology. The reasons for introducing the course and the selection of material included in it are discussed, and its method of presentation and assessment are covered. Detailed syllabi for both the switchgear and protection sections are included, along with the main sources of reference.
A Graphical Method of Solution for Travelling Waves on Transmission Systems with Attenuation
Authors: Barnett P. S.
Published: May 2015

Graphical methods of solution for networks containing transmission lines with attenuation but no distortion are presented. These are similar to those available for the solution of travelling waves on lossless transmission lines using the Schnyder-Bergeron method. The equations used are derived and are of the same form as those used in the method of Schnyder and Bergeron. Examples illustrating the graphical methods are given.
Exact Analysis of Relay Control System with Hysteresis and Coulomb Friction
Authors: Gurusamy G.
Published: May 2015

Exact phase plane analysis of nonlinear system containing two-position relay element, with hysteresis under the consideration of Coulomb friction, is given. Expressions for period and amplitude of stable limit cycle are derived. The effect of Coulomb friction on limit cycle behaviour is also discussed.
Harmonic Analysis of a Triductor — Part 1
Authors: Puri I. K.
Published: May 2015

The third harmonic present in the voltage or current wave-form of a transformer is utilized for the heating of induction furnaces. The secondary power at 150 cycles is controlled with d.c. magnetization of the transformer core. The circuit used shows a different type of B-H curve. This paper explains how this magnetizing curve gives the variation of secondary voltage by changing d.c. control current.
Systems Engineering — A Motivational Approach
Authors: Leininger Gary G.
Published: May 2015

The successful implementation of three motivational innovative teaching mechanisms in an introductory Systems Engineering course is described. The mechanisms are (1) lecture presentation by slide projection, (2) analysis of case studies in Systems Engineering and (3) role playing. An example is presented to demonstrate the degree of sophistication of the case studies and the interplay of graduate assistants.
Orientation and Motivations of Freshman Engineers
Authors: Langholz Gideon , Sekey Andrew A.
Published: May 2015

An orientation course for freshman engineers at Tel-Aviv University, consisting of 21 lectures on a range of subjects given by various speakers from the academic staff and Industry, as well as two surveys on freshmen's changing attitudes towards several branches of engineering, are reported and evaluated.
Design of Optimal Two-Level Logic Networks Using Nor, and, Nand, or Gates
Authors: Frisiani A. L.
Published: May 2015

A direct approach is recalled for the determination of optimal two-level networks using NAND, AND, NOR, OR gates.
Survey of Rotating Electrical Machines and Transformers at British Universities, Polytechnics and Colleges Offering Full-Time Degree Courses
Authors: Harrison H.
Published: May 2015

This survey was initiated to ascertain the emphasis given to these topics in their undergraduate and graduate curricula. The research activity and the text books used have been included in the survey.
Transient Stability of Multimachine Power Systems
Authors: Sastry V. R.
Published: May 2015

Transient stability of multimachine power systems is discussed using the concepts of modern control theory e.g. state variables, Lyapunov functions. The points discussed include the mathematical model, dimension of the state space, effect of damping on stability, validity of neglecting transfer conductances, also suggestions for further work in the area.
The Concept of Electrochemical Potential and its Application to Semiconductor Systems
Authors: Sabah N. H.
Published: May 2015

Electrochemical potential is discussed in terms of concepts that are commonly invoked in the study of semiconductors. It is shown how electrochemical potential provides a natural and fundamental framework for characterizing a PN junction at equilibrium and in the steady state.
A Note on the Compensation Theorem
Authors: Byrne P. C.
Published: May 2015

A simple method for proving the Compensation Theorem for linear active networks is presented and the sensitivity of the current in a branch to changes in impedance of the branch is defined and an expression obtained.
The Analysis of Inverter-Fed Induction Motors
Authors: Murphy Johnm. D.
Published: May 2015

Induction motor operation with a six-step inverter supply is analysed in a manner suitable for existing courses in electrical machines. Steady harmonic torques and harmonic losses are examined by the equivalent circuit approach. The two-axis model is used to determine instantaneous torque and current waveforms and to study transient conditions.
An Integrated Lecture and Laboratory Course in Electrical Machines
Authors: Hindmarsh J.
Published: May 2015

For the age of systems engineering the appropriate requirements of a basic course in electrical machines are considered. Utilizing laboratory time to maximum advantage and coupled to a simple generalized physical-mathematical approach in the lecture course, a scheme is outlined and laboratory equipment is described.
Some Experimental Studies for the Generalized Electrical Machine Theory
Authors: Ma W. F.
Published: May 2015

Experimental studies are devised to demonstrate the fundamental principles underlying the generalized electrical machine theory so that students will be more familiar with the transformer and rotational e.m.f's., together with an improved physical conception of the transformation between rotating and stationary axes.
Power Transformer Constants Affecting its Impulse Voltage Distribution
Authors: El-Arabaty A. M. , Mansour Ezzat A. A. , Said Osama A. M.
Published: May 2015

This work deals with the modification of the known calculating formulae for power transformer constants used for impulse voltage distribution, presents the effect of transformer constants and their modifications on impulse voltage and stress distributions in power transformers, and compares experimental and theoretical results considering measures taken to minimize the difference between them.
What Price Profiles?
Authors: McVey P.J.
Published: May 2015

A ‘profile’ is often recommended as giving more information than a mere statement of degree class. But it will do so only if the variations between subjects are significantly greater than the errors of measurement. A study of several different subjects in electrical engineering suggests that this is not so.
Low Temperature Oxide Deposition Equipment
Authors: Price T. E.
Published: May 2015

The equipment described uses silane to deposit silicon dioxide at 400°C on to a substrate 50 mm in diameter; the oxide may be doped with phosphorus or boron. Details are given of the chemical reactions involved, the construction and operation together with some examples of possible device applications.
Laboratory Aid for Power System Protection Using Operational Amplifiers
Authors: Arrillaga J. , Rollin L.
Published: May 2015

The equipment described contains several modules with variable input signals and auxiliary components together with a family of typical relay function cards. Provision is also made in the front panel for the design of standard or new types of relays using operational amplifiers. The unit is used for protection experiments and final year projects.
Introduction to Microprocessor Systems — Part 2
Authors: Powner E. T. , Escuder M. A. , Depledge P. G.
Published: May 2015

In this, the second article in the series, the interfacing and programming of the microprocessor is discussed; available special-purpose components are reviewed. Aids for system development are covered with reference to their relative merits for the first-time user.
An Elementary Light Pen
Authors: Balmer L.
Published: May 2015

The article describes an elementary light-pen that was built using a Honeywell DDP 516 computer, a standard oscilloscope, and very little additional hardware. Control is by means of light buttons, straight line drawings with continuous or dotted lines can be constructed and numerical information displayed.
A Point-on-Wave Switching-Sequence Unit for Power System Studies
Authors: Efthymiadis A. E.
Published: May 2015

The design and operation of a unit based on integrated circuit counters is described. Single or polyphase switching control is derived from a single phase signal of any frequency. The pulses generated can be used to build up complex controlled sequential switching operations and for triggering associated equipment.
Analogue Control of Impulse Generators
Authors: Banerjea S. R.
Published: May 2015

An application of high voltage testing in undergraduate teaching is described in which a 400-kV impulse generator is operated from a solid state electronic control system. The impulse generator applied repetitive impulses to a spark gap with a consistency of ±0.2% and recorded the result.
Four-Terminal Network Theory Applied to Tap Staggering
Authors: Armstrong R.
Published: May 2015

The principle of voltage control under light-load conditions by tap-staggering parallel transformers is simply and concisely explained by means of four terminal network theory.
The Origin of Forces in Machine-Type Structures
Authors: Jones B. L.
Published: May 2015

Torques in electrical machines are developed largely by iron parts rather than conductors. Simple apparatus has been developed to demonstrate the mechanism of torque production. Analyses in terms of iron surface forces, of changes in coil inductances and of hypothetical air gap conductors are contrasted and compared with measured results.
A Split-Rotor Single-Phase Induction Motor
Authors: Cooper A. J. , Watson D. B.
Published: May 2015

In view of the counter rotating field theory, can a single phase stator winding be used to drive two rotors simultaneously at different speeds in opposite directions, and if so how does the machine perform? The paper puts forward some experimental and theoretical answers to these questions.
Tellegen's Proof of Thevenim's Theorem
Authors: Buijze W.
Published: May 2015

A very simple and elegant proof of Thévenin and Norton's theorem is given.
A Comparison of Reliability: Objective and Conventional Examinations in Electronic Engineering
Authors: McVey P. J.
Published: May 2015

The reliability of several examination papers in Electronic Engineering was tested by the ‘equivalent forms’ method. The ‘objective’ and ‘conventional’ parts were separately compared. When corrected for length, the objective parts were more reliable than the conventional sections in almost every case, but the improvement was not great.
An Eddy Current Phenomenon
Authors: Greig J. , Thompson David
Published: May 2015

An experiment which shows negligible reaction from eddy currents in iron on their inducing field is described. The observations are shown to agree with the extension of Searle's results for the magnetic field of a long current filament in iron to an aggregation of current filaments such as eddy currents.
Several Numerical Methods for Matrix Inversion
Authors: Lo K. L.
Published: May 2015

This paper describes several numerical methods for matrix inversion. The computational steps and the relative merits of the methods are discussed. A section is also particularly devoted to the inversion of complex matrices on mini-computers.
On the Maximum Power Transfer Theorem
Authors: Narayanan H.
Published: May 2015

A reformulation of the maximum power transfer theorem, in terms of terminal conditions of the network corresponding to maximum power delivery, is given. Applications of this reformulation for a variety of terminations are discussed for the purely resistive and the sinusoidal steady-state cases.
Extension of the Initial Value Theorem
Authors: Henderson A.
Published: May 2015

A formula is derived which gives the value of the first and all higher derivatives at the moment t = 0+ directly from the Laplace transform.
Equilibrium Conditions in Electrostatic Fields
Authors: Hammond P.
Published: May 2015

It is shown that Thomson's theorem describes the equilibrium energy of a system. If the charge is held constant, this energy is a minimum, but if the potential is held constant the energy is a maximum. The theorem can therefore be used to give upper and lower bounds to the electrostatic energy.
An Improved RC Twin-T Null Network
Authors: Ho C. F.
Published: May 2015

A modified RC twin-T null network is discussed. It differs from the conventional circuit in that a wide range of notch frequency can be tuned by a single potentiometer. Closely matched components are not required and symmetric notch response is maintained as the frequency is tuned.
Frequency Multiplier Using Phase-Wound Induction Machine
Authors: Varasundharosoth B. , Watson D. B.
Published: May 2015

This article suggests a method of obtaining power at 100 Hz, 150 Hz and 200 Hz from a supply frequency of 50 Hz using a 3-phase wound type induction machine arranged as a frequency convertor.
Planning Microprocessor Courses and a Laboratory in a University Environment
Authors: Athani V. V.
Published: May 2015

This paper begins by stressing the need for microprocessor education. It then gives details of the microprocessor courses at I.I.T.-Bombay. Considerations governing microprocessor laboratory planning for instructional, research and consultancy work are given. The paper concludes with a model list of equipment for a microprocessor laboratory in a University.
Two-Port Parameter Conversion
Authors: Adby P. R.
Published: May 2015

Most circuit theory textbooks tabulate two-port parameter conversion by separately listing 30 matrix entries. This presentation conceals important properties relevant to efficient application. Many conversions are numerically equal and a simplified tabulation requires 19 entries only. Also, conversions to and from A parameters are cyclic, leading to computational efficiency.
A Power Assignment to Sources and Passive Branches of a Network, Based on Tellegen's Theorem
Authors: Moreno E. , Rodriguez-Izquierdo G.
Published: May 2015

This paper describes the principles of a power assignment based on Tellegen's and superposition theorems, and demonstrates its properties. Some extensions of this theory are also given for the sinusoidal steady state and for mechanical analogs.
A Few Liapunov Functions for a Synchronous Generator Infinite Bus Power System Problem
Authors: Rahim A.H.M.A. , Rahman M. M.
Published: May 2015

The transient stability of a single machine infinite bus power system problem was examined through the direct method of Liapunov. It was observed, through the direct method, that the system can be operated at a larger exciter gain if an additional feedback signal proportional to shaft speed deviation is used.
The Electric Arc Furnace—A Useful Teaching System
Authors: Armstrong R.
Published: May 2015

A simplified study of problems relating to an electric arc furnace system is presented as a means of illustrating a variety of principles required to produce a meaningful solution. Features discussed in the article are: Rotating magnetic fields; Linearisation technique; Time domain solution; Frequency domain solution; Locus diagram; Stability limit.
A Laboratory Experiment on the Thermal Behaviour of a Power Transistor
Authors: Hanrahan H. E.
Published: May 2015

An experiment is described in which a practical thermal equivalent circuit of a power transistor-heatsink combination is found. The theory underlying the experiment is presented and the apparatus is described. The thermal parameters are obtained from a cooling curve.
Interactive Load Flow Program for Electrical Engineering Undergraduate Students
Authors: Alden Robert T. H.
Published: May 2015

This is an interactive FORTRAN program for network assembly and solution using Gauss-Seidel iteration. Maximum size is sixteen buses and eighteen lines with student modification of size, configuration, and loading, starting from base cases defined by the instructor. Optionally the results may be displayed on a single line diagram.
A Microprocessor Laboratory System to Process Analog Signals
Authors: Bolton A. G.
Published: May 2015

This paper describes a microprocessor laboratory system with analog input and output which has been included within an undergraduate course for the last four years. Aspects considered include the microprocessor system, literature and introductory experiments undertaken by the students.
The History and Operation of the Technician Education Council Programmes in Colleges of Technology in the United Kingdom
Authors: Birbeck R.
Published: May 2015

A brief account is given of the reasons for the changes which have taken place in the last few years in technician further education. The structure of the new courses is outlined, and advantages and disadvantages are listed.
Teaching and Research — The Role of the Industrial Unit
Authors: Dorey A. P.
Published: May 2015

Engineering education and research must be related to both engineering practice and theory. An Industrial Unit engaging in short-term contract research provides a complementary activity to balance conventional academic research and teaching to the benefit of the full range of activities.
A Teaching Company Programme
Authors: Boardman D.
Published: May 2015

The paper contains a description of the Science Research Council and Department of Industry funded Teaching Company Scheme which operates through Teaching Company programmes where an educational establishment participates in an industrial programme, to achieve a substantial and comprehensive change in manufacturing, which benefits the company, the academics and Teaching Company Associates.
A Note on Stability Conditions of Active RC Networks
Authors: Ho C. F.
Published: May 2015

Stability conditions with respect to capacitances for canonical second-order active RC networks described by Holmes have been discussed. An extension to the theorem for high order systems is then presented. An illustrative example for a three-capacitor circuit is given.
Normal Modes on Uniform, Multi-Conductor, Transmission Lines
Authors: Anderson R.
Published: May 2015

A simple method for calculating the normal modes of propagation along a multi-conductor transmission line having perfect conductors is given. The technique is illustrated by a laboratory exercise in which the normal modes along a slab line structure are investigated by means of a solid conduction analogue.
Microprocessor Laboratory Procedure within a Control Course
Authors: Bolton Alan G.
Published: May 2015

The paper presents an approach to incorporating microprocessors within the laboratory procedure for a control course. Emphasis is placed on the relationship between the behaviour of the dynamic system which incorporates the microprocessor and the program algorithms. A system identification implementation is discussed.
Multilevel Nand (NOR) Implementation of Logical Functions
Authors: Halder A. K.
Published: May 2015

A scheme for implementing multilevel NAND (NOR) network of a logical function is presented. The method avoids the need for application of De Morgan's theorem and eliminates the tedium of drawing AND-OR logic diagrams. The analysis of NAND (NOR) logic diagrams to determine the output functions in AND-OR logic is also made easier by the method.
Laboratory Work Stimulates Interest in Electromechanics
Authors: Watson D. B. , Byers D. J. , Archer R. W. , Hegglun I. V. , Lord T. R. , Milner I. P.
Published: May 2015

The paper describes project-type experiments devised to arouse interest in electromechanics, a topic for which students usually have very little feeling. Students are motivated by the immediate relevance of each experiment. The involvement of the supervisor as a collaborator, student and supervisor reactions, and the method of assessment, are discussed.
Numerical Conformal Mapping for Undergraduates
Authors: Warner G. , Anderson R.
Published: May 2015

A numerical approach to conformal mapping is discussed which is conceptually simple and requires only elementary mathematics and simple programming. The technique is illustrated with practical problems well within the ability of an undergraduate student. Sufficient detail is given for the examples to be of immediate in-course use.
The Use of Search Coils for Magnetic Measurements
Authors: Bhargava S. C.
Published: May 2015

The basic principle of search coils is explained by reference to the integral form of Maxwell's equation. The salient features of instrumentation, necessary for search coil applications, are discussed, followed by a brief description of a few typical examples of magnetic measurements by a variety of search coils.
Harmonic Elimination
Authors: Arrillaga J.
Published: May 2015

A review of the techniques presently available for the control of harmonic content in three-phase a.c.-d.c. convertors is presented. It includes increased pulse numbers, harmonic filters and harmonic injection. Recent trends and main problem areas encountered in filter design are given special consideration.
A CMOS Breadboard Gate Array for Educational and R. and D. Purposes
Authors: Hurst S. L.
Published: May 2015

Master-chip gate arrays are becoming an accepted means of producing small quantities of special integrated circuits for research and project duties. This paper considers the adoption of novel logic configurations, termed universal-logic-modules, the particular advantages of which will be discussed in this paper.
Liquid Crystal Displays as a Topic for Undergraduate Laboratory Work
Authors: Lawrenson B.
Published: May 2015

The assembly of a simple twisted nematic liquid crystal display test cell is described and an account is given of some investigations that may be undertaken using it. Details for making a working seven-segment display are given.
A Single-Bit Microcomputer Experiment
Authors: Hodgson R. M. , Hamilton E. J.
Published: May 2015

This experiment uses a processor originally developed as a solid-state substitute for relay logic controllers. The repertoire of sixteen instructions perform logical operations on a one-bit bidirectional data bus. The simplicity of the instruction set and device structure make it a useful instructional vehicle for microcomputer concepts.
Analog to Digital Conversion Using a Microprocessor
Authors: Chadwick A. M. , Herdman W.
Published: May 2015

This paper outlines a technique for demonstrating three types of A/D converter using a microprocessor. As an experiment it introduces the student to situations where a microprocessor forms an integral part of a system. The program can be developed by students or stored in ROM and used as demonstrations.
A Microcomputer-Controlled Experiment to Measure Semiconductor Material Properties
Authors: Singer K. E. , McKell H. D.
Published: May 2015

An undergraduate experiment has been devised to enable the conductivity and Hall coefficient of germanium to be measured over a range of temperatures. Control of the experiment and the collection, initial reduction and display of data is managed by a desktop computer. The experiment both reinforces lecture material on fundamental conduction processes in semiconductors, and also introduces students to modern automatic measurement systems.
A Microcomputer-Assisted Power System Laboratory
Authors: Richards Gill G. , Huckabee Paul T.
Published: May 2015

A microcomputer-assisted instructional power systems laboratory, featuring digital data acquisition, has been developed for the electric power curriculum at Lousiana State University. Each Student bench setup interfaces traditional rotating power equipment with a microcomputer console for the sampling and display of electrical quantities. This approach has increased the scope of experiments and created a more realistic laboratory atmosphere.
An Advanced Electronics Teaching Laboratory
Authors: Goodman R. M. F. , Taylor G. E. , Winfield A. F. T.
Published: May 2015

The rapid advancement of electronics technology means that undergraduate teaching laboratories should be frequently reviewed. This philosophy led to the new third-year laboratory structure described in this paper. This was implemented in October 1981 as an integral part of a four-year course and, in a radical departure from standard practice, involves open-ended experiments including both software and hardware design.