Heat transfer intensification in an actuated heat exchanger submitted to an imposed pressure drop

This paper is dedicated to the analysis of the improvement of heat transfer and the reduction of the pressure losses induced by the use of an active exchanger of millimeter size in a cooling loop. For pressure conditions imposed at the terminals of such a mini-channel whose upper wall is deformed by a progressive sinusoidal wave and for low Reynolds numbers (Re < 1000), we study the influence of the deformation parameters on the thermo-hydraulic performance of the exchanger (flow, heat transfer). The mechanical power applied to the deformed wall is connected to these parameters as well as to the pressure difference imposed by the external pump. The overall performance increases slightly with the value of the mechanical power up to a critical value for a given wall corrugation. Nevertheless, overall performance is up to 2 orders of magnitude higher than conventional static corrugated channels.

Characterization of Initial Parameter Information for Lifetime Prediction of Electronic Devices

Newly manufactured electronic devices are subject to different levels of potential defects existing among the initial parameter information of the devices. In this study, a characterization of electromagnetic relays that were operated at their optimal performance with appropriate and steady parameter values was performed to estimate the levels of their potential defects and to develop a lifetime prediction model. First, the initial parameter information value and stability were quantified to measure the performance of the electronics. In particular, the values of the initial parameter information were estimated using the probability-weighted average method, whereas the stability of the parameter information was determined by using the difference between the extrema and end points of the fitting curves for the initial parameter information. Second, a lifetime prediction model for small-sized samples was proposed on the basis of both measures. Finally, a model for the relationship of the initial contact resistance and stability over the lifetime of the sampled electromagnetic relays was proposed and verified. A comparison of the actual and predicted lifetimes of the relays revealed a 15.4% relative error, indicating that the lifetime of electronic devices can be predicted based on their initial parameter information.

Can electronic stability control replace studded tyres?

Based on recent studies, this paper examines whether an increased use of electronic stability control can replace studded tyres. A re-analysis of a study that evaluated the effects on accidents of changes in the use of studded tyres in major cities in Norway is presented. It is found that if all cars have electronic stability control, the use of studded tyres can be reduced to about 15 percent before any increase in the number of accidents occurs. Even if studded tyres were eliminated entirely, any increase in the number of accidents is likely to be considerably smaller than it would have been if electronic stability control had never been invented.

Trends in orthorhombic crystal field parameters for trivalent rare-earth ions in high-Tc superconductors REBa₂Cu₃O₇-δ - correct interpretation based on standardization

Trends in orthorhombic crystal field parameters (CFPs) reported for RE(3+) ions in high-T(c) superconductors REBa(2)Cu(3)O(7-)(δ) are considered. The cases of trends based on the CFP sets belonging to different regions of CF parameter space are identified and clarified. The crucial feature of such correlated alternative CFP sets is their intrinsic incompatibility. This makes meaningless direct comparisons of such CFP sets and thus presentations of CFP trends involving a mixture of alternative CFP sets. The aim of this paper is to ascertain that correct interpretation of trends in orthorhombic CFPs must be based on standardization. Examples of graphs inappropriately representing trends in orthorhombic CFPs reported for REBa(2)Cu(3)O(7-)(δ) compounds are considered and the corrected graphs based on the standardized CFP sets are provided.

Wideband laser locking to an atomic reference with modulation transfer spectroscopy

We demonstrate that conventional modulated spectroscopy apparatus, used for laser frequency stabilization in many atomic physics laboratories, can be enhanced to provide a wideband lock delivering deep suppression of frequency noise across the acoustic range. Using an acousto-optic modulator driven with an agile oscillator, we show that wideband frequency modulation of the pump laser in modulation transfer spectroscopy produces the unique single lock-point spectrum previously demonstrated with electro-optic phase modulation. We achieve a laser lock with 100 kHz feedback bandwidth, limited by our laser control electronics. This bandwidth is sufficient to reduce frequency noise by 30 dB across the acoustic range and narrows the imputed linewidth by a factor of five.

Manufacture and characterization of high Q-factor inductors based on CMOS-MEMS techniques

A high Q-factor (quality-factor) spiral inductor fabricated by the CMOS (complementary metal oxide semiconductor) process and a post-process was investigated. The spiral inductor is manufactured on a silicon substrate. A post-process is used to remove the underlying silicon substrate in order to reduce the substrate loss and to enhance the Q-factor of the inductor. The post-process adopts RIE (reactive ion etching) to etch the sacrificial oxide layer, and then TMAH (tetramethylammonium hydroxide) is employed to remove the silicon substrate for obtaining the suspended spiral inductor. The advantage of this post-processing method is its compatibility with the CMOS process. The performance of the spiral inductor is measured by an Agilent 8510C network analyzer and a Cascade probe station. Experimental results show that the Q-factor and inductance of the spiral inductor are 15 at 15 GHz and 1.8 nH at 1 GHz, respectively.

Communication performance analysis and comparison of two patterns for data exchange between nodes in WorldFIP fieldbus network

Data exchange patterns between nodes in WorldFIP fieldbus network are quite important and meaningful in improving the communication performance of WorldFIP network. Based on the basic communication ways supported in WorldFIP protocol, we propose two patterns for implementation of data exchange between peer nodes over WorldFIP network. Effects on communication performance of WorldFIP network in terms of some network parameters, such as number of bytes in user's data and turn-around time, in both the proposed patterns, are analyzed at length when different network speeds are applied. Such effects with the patterns of periodic message transmission using acknowledged and non-acknowledged messages, are also studied. Communication performance in both the proposed patterns are analyzed and compared. Practical applications of the research are presented. Through the study, it can be seen that different data exchange patterns make a great difference in improving communication efficiency with different network parameters, which is quite useful and helpful in the practical design of distributed systems based on WorldFIP network.

Proportional hazards models with discrete frailty

We extend proportional hazards frailty models for lifetime data to allow a negative binomial, Poisson, Geometric or other discrete distribution of the frailty variable. This might represent, for example, the unknown number of flaws in an item under test. Zero frailty corresponds to a limited failure model containing a proportion of units that never fail (long-term survivors). Ways of modifying the model to avoid this are discussed. The models are illustrated on a previously published set of data on failures of printed circuit boards and on new data on breaking strengths of samples of cord.

Coincidence error during measurement of cellular osmotic properties by the electrical sensing zone method

Coincidence is a phenomenon that occurs when electrical sensing zone instruments fail to temporally resolve two or more particles passing through the sensing zone in close proximity. We have investigated the potential for coincidence errors to confound the estimation of cellular osmotic properties. A mathematical model was developed to predict the magnitude of coincidence error as a function of the instrument sensing volume, the cell concentration, and the degree of cell aggregation. The model was validated in a representative instrument (Coulter counter model Z2, with a 100-micron aperture tube), for which the sensing volume was estimated to be approximately 2 nL. Furthermore, we measured the degree of cell aggregation in trypsinized cultures of MIN6 cells, and used these data to estimate the effect of coincidence on MIN6 cell volume measurements. Finally, we simulated water transport experiments, and determined the sensitivity of estimates of the osmotically inactive volume and the membrane water permeability to coincidence error. Our results revealed that coincidence can result in significant overestimation of these two parameter values for high cell concentrations and for suspensions containing cell aggregates.

Phase-locked 10 MHz reference signal for frequency domain time-resolved fluorescence measurements

A complete electronic system that is suitable for use in megahertz frequency domain time-resolved fluorescence instruments based on mode-locked lasers is described. The circuit produces a 10 MHz signal, phase locked to the mode-locked laser pulse frequency, which is required by many commercial frequency synthesizers as the external reference signal. This device is particularly useful in conjunction with ultrafast gated intensified charge coupled device cameras capable of being frequency modulated for time-resolved fluorescence imaging.

A comparative hierarchical decision framework on toxics use reduction effectiveness for electronic and electrical industries

Analytic Hierarchical Process (AHP) has been used in this study as a decision-making model to investigate the potential benefits of implementing a Toxics Use Reduction Act (TURA) in California, based on outcome measures of similar programs in other states, with a focus on the Massachusetts TURA established in 1989. A comparative assessment of trends in the Toxic Release Inventory (TRI) characteristics, economic and census statistics, and the environmental performance of electronics and electrical industries in the two states indicated that programs already implemented in California are effective in achieving the goals of the generic Massachusetts TURA. The results of this study provide a crucial baseline for evaluating the effectiveness of industry-targeted waste reduction policies such as California's new Universal Waste regulation, which covers the disposal of domestic electronic products, effective February 9, 2006.

Retention of different sizes of electronic identification boluses in the forestomachs of sheep1,2

Twelve types of electronic identification ruminal boluses of different dimensions were used to obtain a model for predicting their retention in the forestomachs of sheep. Boluses (n = 1,662) were made of ceramic materials, and their dimensions varied in o.d. (9 to 21 mm), length (37 to 68 mm), volume (2.5 to 21.0 mL), and specific gravity (0.85 to 3.91). Each bolus contained a half-duplex, standardized, glass-encapsulated transponder (32 x 3.8 mm). Boluses were administered to sheep (n = 1,497) of different ages by using the appropriate balling guns, and their retention under semiintensive conditions was recorded for at least 2 yr. When a bolus was lost, the sheep was rebolused with a heavier bolus. All sheep wore 2 plastic ear tags: one for the official control of health programs and the other for farm use. To determine the anatomical limit for a bolus passing through the gastrointestinal tract, the size of the reticulo-omasal orifice was measured in 46 adult sheep (male, n = 14; female, n = 32) that died by causes not related to bolus administration during the experiment. No signs of disease or growth alteration were detected in the bolused sheep. Total ear tag losses during the experiment period were 7.5% on average. Bolus retention (5 to 100%) varied according to bolus features and age of the sheep, but it showed a plateau after 18 mo. Inadequately dimensioned boluses were regurgitated or passed through the gastrointestinal tract and were excreted with the feces. The diameter of the reticulo-omasal orifice in adult sheep differed between male and female (23.1 and 21.8 mm, respectively; P < 0.01) and was greater than the o.d. of the retained boluses. Retention rate was predicted from bolus weight and volume by a logistic regression (R2 = 0.997; P < 0.001). When retention data from the literature (59.0 to 100%) were included in the model, the adjustment was slightly lower (R2 = 0.967). As a result, the minimum bolus weight estimated to reach a 99.5% retention rate in sheep varied between 16 and 45 g when volume varied between 3 and 22 mL, for boluses with a specific gravity between 2.0 and 5.2. In conclusion, bolus retention rate in sheep varied dramatically according to their features. For safe and efficient retention of electronic identification boluses in sheep, boluses of small volume and diameter (e.g., < 15 mm) with specific gravity and weight greater than 3.0 and 20 g, respectively, are recommended.

Fast identification of ten clinically important micro-organisms using an electronic nose

AIMS

To evaluate the electronic nose (EN) as method for the identification of ten clinically important micro-organisms.

METHODS AND RESULTS

A commercial EN system with a series of ten metal oxide sensors was used to characterize the headspace of the cultured organisms. The measurement procedure was optimized to obtain reproducible results. Artificial neural networks (ANNs) and a k-nearest neighbour (k-NN) algorithm in combination with a feature selection technique were used as pattern recognition tools. Hundred percent correct identification can be achieved by EN technology, provided that sufficient attention is paid to data handling.

CONCLUSIONS

Even for a set containing a number of closely related species in addition to four unrelated organisms, an EN is capable of 100% correct identification.

SIGNIFICANCE AND IMPACT OF THE STUDY

The time between isolation and identification of the sample can be dramatically reduced to 17 h.

Application of the electronic nose to the classification of resistance to Western flower thrips in chrysanthemums

A metal oxide sensor-based electronic nose was tested for its ability to discriminate among chrysanthemum cultivars with varying degrees of resistance to western flower thrips (WFT), based on volatile chemicals released from cut leaves. Cultivars that were susceptible, intermediate, or resistant to WFT [based on mean cultivar rank (MCR)] were used as standards, and were correctly classified (> 90%) by using discriminant function analysis. Several cultivars with unknown resistance were classified based on the standards, and were used as standards in a subsequent trial to classify other unknowns. The results of this study demonstrate some agreement between the WFT resistance categories as designated by the electronic nose and results of feeding bioassays (MCR), suggesting that this technique may serve as a useful screening tool for WFT resistance.

Electronic nose based tea quality standardization

In this paper we have used a metal oxide sensor (MOS) based electronic nose (EN) to analyze five tea samples with different qualities, namely, drier month, drier month again over-fired, well fermented normal fired in oven, well fermented overfired in oven, and under fermented normal fired in oven. The flavour of tea is determined mainly by its taste and smell, which is generated by hundreds of Volatile Organic Compounds (VOCs) and Non-Volatile Organic Compounds present in tea. These VOCs are present in different ratios and determine the quality of the tea. For example Assamica (Sri Lanka and Assam Tea) and Assamica Sinesis (Darjeeling and Japanese Tea) are two different species of tea giving different flavour notes. Tea flavour is traditionally measured through the use of a combination of conventional analytical instrumentation and human or ganoleptic profiling panels. These methods are expensive in terms of time and labour and also inaccurate because of a lack of either sensitivity or quantitative information. In this paper an investigation has been made to determine the flavours of different tea samples using an EN and to explore the possibility of replacing existing analytical and profiling panel methods. The technique uses an array of 4 MOSs, each of, which has an electrical resistance that has partial sensitivity to the headspace of tea. The signals from the sensor array are then conditioned by suitable interface circuitry. The data were processed using Principal Components Analysis (PCA), Fuzzy C Means algorithm (FCM). We also explored the use of a Self-Organizing Map (SOM) method along with a Radial Basis Function network (RBF) and a Probabilistic Neural Network classifier. Using FCM and SOM feature extraction techniques along with RBF neural network we achieved 100% correct classification for the five different tea samples with different qualities. These results prove that our EN is capable of discriminating between the flavours of teas manufactured under different processing conditions, viz. over-fermented, over-fired, under fermented, etc.

Comparison of various safety guidelines for electronic article surveillance devices with pulsed magnetic fields

The paper uses the two methods suggested in both the ICNIRP and proposed IEEE safety guidelines for compliance testing of security systems based on time-varying magnetic fields being introduced for electronic article surveillance (EAS), radiofrequency identification, and other applications. For nonsinusoidal pulses that are often used, the two procedures are to treat the exposure as a multifrequency exposure with various frequency components or to calculate the peak induced current densities or electric fields treating the highest of the pulses of duration t(p) as a single frequency, half sinusoid of the same duration and frequency 1/(2t(p)). Using either of the procedures, the induced current densities (J) or electric fields (E) are compared to the basic restrictions on J or E for compliance testing. Using a heterogeneous, tissue-classified anatomic model of the human body, we calculate the induced J and E for the various tissues for a realistic, EAS system for two typical nonsinusoidal pulses to show that the two methods give substantially different results. While the approximate but simpler method of treating the pulse as a half sinusoid results in peak induced J or E that may be compliant with safety guidelines, the rigorous method of treating such exposures as multifrequency exposures gives induced current densities or electric fields that may be up to twice as large, thus making such systems potentially noncompliant with the safety guidelines. Since it is more accurate, it is suggested that safety assessment based on the Fourier analysis leading to multifrequency components be used for compliance testing of such devices.

Proposed minimum requirements for the operational characteristics and testing of submersible atmosphere monitoring and control units

The design of a submersible and its myriad subsystems is a complex undertaking made more difficult by the interval between new designs. Special applications also tax the life support designer, such as diver lock-out submersibles, which are far more complex than one-atmosphere vehicles. The long intervals between designs generally means that a new generation of designers will be approaching the problems without the benefit of the knowledge and experience of the past generation of designers. This new generation of designers often has greatly improved technologies and materials at hand. Yet in the application of the new technology, life support issues that were addressed and resolved in the old and proven designs get lost in the process of redesign due to the lack of experience in the life support arena. Competent engineers operating outside their normal area of expertise can generate costly or even deadly mistakes. For this reason a set of performance requirements that details the critical functions of the life support systems is needed. Atmosphere control electronics can seriously impact the safety of the submersible crew. The triple dangers of fire, toxicity, and asphyxia demand that the electronics that monitor and control the submarine compartment atmosphere have certain characteristics. These characteristics are easily captured in a performance requirement. This article will present a set of proposed minimum performance requirements, with the goal of establishing a dialog for the creation of guidelines for the classification, rating, design, and testing of embedded electronics for life support systems used in submersible applications. These guidelines will serve as the foundation for the later creation of a set of industry specifications.

Proposed minimum requirements for the operational characteristics and testing of closed circuit life support system control electronics

The popularization and transformation of scuba diving into a broadly practiced sport has served to ignite the interest of technically oriented divers into ever more demanding areas. This, along with the gradual release of military data, equipment, and techniques of closed circuit underwater breathing apparatus, has resulted in a virtual explosion of semiclosed and closed circuit systems for divers. Although many of these systems have been carefully thought out by capable designers, the impulse to rush to market with equipment that has not been fully developed and carefully tested is irresistible to marketers. In addition, the presence of systems developed by well-intentioned and otherwise competent designers who are, nonetheless, inexperienced in the field of life support can result in the sale of failure-prone equipment to divers who lack the knowledge and skills to identify deficiencies before disaster occurs. For this reason, a set of industry standards establishing minimum requirements and testing is needed to guide the designers of this equipment, and to protect the user community from incomplete or inadequate design. Many different technologies go into the development of closed circuit scuba. One key area is the design of electronics to monitor and maintain the critical gas mixtures of the closed circuit loop. Much of the system reliability and inherent danger is resident in the design of the circuitry and the software (if any) that runs it. This article will present a set of proposed minimum requirements, with the goal of establishing a dialog for the creation of guidelines for the classification, rating, design, and testing of embedded electronics for life support systems used in closed circuit applications. These guidelines will serve as the foundation for the later creation of a set of industry specifications.

Accuracy of electronic implant torque controllers following time in clinical service

Tightening of the screws in implant-supported restorations has been reported to be problematic, in that if the applied torque is too low, screw loosening occurs. If the torque is too high, then screw fracture can take place. Thus, accuracy of the torque driver is of the utmost importance. This study evaluated 4 new electronic torque drivers (controls) and 10 test electronic torque drivers, which had been in clinical service for a minimum of 5 years. Torque values of the test drivers were measured and were compared with the control values using a 1-way analysis of variance. Torque delivery accuracy was measured using a technique that simulated the clinical situation. In vivo, the torque driver turns the screw until the selected tightening torque is reached. In this laboratory experiment, an implant, along with an attached abutment and abutment gold screw, was held firmly in a Tohnichi torque gauge. Calibration accuracy for the Tohnichi is +/- 3% of the scale value. During torque measurement, the gold screw turned a minimum of 180 degrees before contact was made between the screw and abutment. Three torque values (10, 20, and 32 N-cm) were evaluated, at both high- and low-speed settings. The recorded torque measurements indicated that the 10 test electronic torque drivers maintained a torque delivery accuracy equivalent to the 4 new (unused) units. Judging from the torque output values obtained from the 10 test units, the clinical use of the electronic torque driver suggests that accuracy did not change significantly over the 5-year period of clinical service.

An in vitro evaluation of the accuracy of the root ZX in the presence of various irrigants

The purpose of this study was to evaluate the accuracy of the Root ZX in vitro in the presence of a variety of endodontic irrigants. The in vitro model, described by Donnelly, consisted of refrigerated gelatin made with 0.9% sodium chloride instead of water. The following irrigants were tested: 2% lidocaine with 1:100,000 epinephrine, 5.25% sodium hypochlorite, RC Prep, liquid EDTA, 3% hydrogen peroxide, and Peridex. A total of 30 extracted, single-rooted teeth were used. The experimental measurements in the presence of the various irrigants were compared with the actual canal lengths. The present data indicate that the Root ZX electronic apex locator reliably measured canal lengths to within 0.31 mm and that there was virtually no difference in the length determination as a function of the seven irrigants used. These results strongly support the concept that the Root ZX is a useful, versatile, and accurate device for the determination of canal lengths over a wide range of irrigants commonly used in the practice of endodontics.

[Analysis of the place of regulation of C-11 transmitters at the Tele-electronic Works "Telkom-Telfa" in Bydgoszcz from the point of view of visual hygiene]

The authors performed a detailed analysis of 100 positions of regulation of the C-11 transmitters in the "Telcom-Telfa" ++Tele-electronic Works in Bydgoszcz. It was determined that the requirements for the condition of the eyes and the lighting at this workstand are considerable. Conclusions and recommendations tending to improvement of the working conditions are drawn up. Proposed is eventual rationale leading to the reduction of the eyestrain and facilitation of the work.

Portable maximum respiratory pressure measurement--a comparison with laboratory techniques

We have evaluated a new, hand-held, electronic device to measure maximal respiratory pressures, and compared its performance in normal subjects against two pre-existing methods. This new device produces accurate, reproducible results and has the advantages of easy use and portability, which allow it to be used at the patient's bedside, outpatient clinic or pulmonary function laboratory.

[Hygienic evaluation of women's work in radio-manufacturing industry]

Conditions and character of labour of women working in revolver production are determined by exposure to noise, contact with cooling oils, static field, monotony, hypodynamics, tension of the visual analyser, which leads to the stress of the functional systems of the organism, development of fatigue, decrease in labour productivity, increased morbidity level with temporary loss of capacity for work. A complex of health-improving measures on normalization of occupational factors, rationalization of labour and rest regimen, implementation of which would promote increase in the capacity for work of women engaged in revolver production.

[Relation between health status of female assemblers and the degree of occupational fatigue]

Fatigue, the functional status and morbidity of women-assemblers of the watches and shoes have been investigated. Assessment of fatigue was based on the subjective parameters. Reliable changes in morbidity were not observed in women of 20-30 years of age with a high degree of fatigue, while in the group of women of 31-40 years of age an increase in the frequency of diseases of cardio-vascular, bone-muscular and peripheral nervous systems were observed. Correlation coefficients of the degree of fatigue were 0.42 for the frequency, and 0.37 for the number of days of staying at home due to the loss of the working ability. In the group of women of 41-50 years of age this correlation is less expressed, though the morbidity level is high. The leading factors of fatigue and morbidity in these professional groups are as follows: volume and intensity of work, visual stress and low-mobility position.

[Medico-biological aspects of the effect of modulated high-frequency radiation]

The study demonstrated some deviations in the health state of radio equipment controllers exposed to modulated high-frequency electromagnetic radiation, they had higher rates of functional disorders of the CNS and cardiovascular diseases, compared to the control group. It was experimentally found that the animals had different reaction of the peripheric blood to the effect of code-modulated electromagnetic radiation and nonmodulated oscillations.

A quality study of 35 mm, miniaturization of full-size radiographic film

Twenty-one radiologists with 6 months--25 years experience judged the quality and the possibilities for the routine use of miniaturized full-size radiographic films for long time archiving. Twenty-eight examinations on full-size radiographs were photographed on 35 mm. film. After mounting in transparent jackets, the miniaturized films were read with enlarging equipment and diagnoses and quality noted. Comparison was later made with the originals. The consensus was that the quality of the miniaturized film was good enough to permit their use for long-term archiving purposes and subsequent comparison with future full-size radiographs. The use of reading equipment was not considered tedious.

Assembly and inspection of microelectronic systems

Two experiments were performed to determine how human performance in the assembly and inspection of microelectronic devices might be improved. The first revealed that use of tools specifically designed to minimize the probability of human error resulted in significant reductions in errors in the handling of silicon wafers. The second indicated that providing the operator with a visual frame of reference resulted in detection of a significantly greater percentage of the defects present in photo masks of the type used in production of microelectronic circuits.