Integrated chip-size antennas for wireless microsystems: Fabrication and design considerations

This paper reports on fabrication and design considerations of an integrated folded shorted-patch chip-size antenna for applications in short-range wireless microsystems and operating inside the 5–6 GHz ISM band. Antenna fabrication is based on wafer-level chip-scale packaging (WLCSP) techniques and consists of two adhesively bonded glass wafers with patterned metallization and through-wafer electrical interconnects. Via formation in glass substrates is identified as the key fabrication step. Various options for via formation are compared and from these, a 193 nm excimer laser ablation is selected for fabrication of the antenna demonstrator. The fabricated antenna has dimensions of 4 mm × 4 mm × 1 mm, measured operating frequency of 5.05 GHz with a bandwidth of ∼200 MHz at the return loss of −10 dB and a simulated radiation efficiency of 60% were achieved.     

Guided local search as a network planning algorithm that incorporates uncertain traffic demands

A search based heuristic for the optimisation of communication networks where traffic forecasts are uncertain and the problem is NP-complete is presented. While algorithms such as genetic algorithms (GA) and simulated annealing (SA) are often used for this class of problem, this work applies a combination of newer optimisation techniques specifically: fast local search (FLS) as an improved hill climbing method and guided local search (GLS) to allow escape from local minima. The GLS + FLS combination is compared with an optimised GA and SA approaches. It is found that in terms of implementation, the parameterisation of the GLS + FLS technique is significantly simpler than that for a GA and SA. Also, the self-regularisation feature of the GLS + FLS approach provides a distinctive advantage over the other techniques which require manual parameterisation. To compare numerical performance, the three techniques were tested over a number of network sets varying in size, number of switch circuit demands (network bandwidth demands) and levels of uncertainties on the switch circuit demands. The results show that the GLS + FLS outperforms the GA and SA techniques in terms of both solution quality and optimisation speed but even more importantly GLS + FLS has significantly reduced parameterisation time.     

Modelling foot height and foot shape-related dimensions

The application of foot anthropometry to design good-fitting footwear has been difficult due to the lack of generalised models. This study seeks to model foot dimensions so that the characteristic shapes of feet, especially in the midfoot region, can be understood. Fifty Hong Kong Chinese adults (26 males and 24 females) participated in this study. Their foot lengths, foot widths, ball girths and foot heights were measured and then evaluated using mathematical models. The results showed that there were no significant allometry (p > 0.05) effects of foot length on ball girth and foot width. Foot height showed no direct relationship with foot length. However, a normalisation with respect to foot length and foot height resulted in a significant relationship for both males and females with R² greater than 0.97. Due to the lack of a direct relationship between foot height and foot length, the current practice of grading shoes with a constant increase in height or proportionate scaling in response to foot length is less than ideal. The results when validated with other populations can be a significant way forward in the design of footwear that has an improved fit in the height dimension.     

A moving horizon approach to input design for closed loop identification

The identification of high fidelity models is a critical element in the implementation of high performance model predictive control (MPC) applications in the industry. These controllers can vary in size with input–ouput dimensions ranging from 5 × 10 to 50 × 100. Identifying models of this scale accurately is a time consuming and demanding exercise. We present a novel approach wherein an information rich test signal is generated in closed loop by maximizing the MPC objective, as opposed to minimization that is done in the standard controller. We show that the proposed input design approach is similar to T-optimal (trace optimal) experiment design method. Our approach automatically accounts for the input and output constraints and is implemented in a moving horizon manner. It is demonstrated through simulation examples on both well and ill-conditioned processes.     

Early-stage atherosclerosis detection using deep learning over carotid ultrasound images

This paper proposes a computer-aided diagnosis tool for the early detection of atherosclerosis. This pathology is responsible for major cardiovascular diseases, which are the main cause of death worldwide. Among preventive measures, the intima-media thickness (IMT) of the common carotid artery stands out as early indicator of atherosclerosis and cardiovascular risk. In particular, IMT is evaluated by means of ultrasound scans. Usually, during the radiological examination, the specialist detects the optimal measurement area, identifies the layers of the arterial wall and manually marks pairs of points on the image to estimate the thickness of the artery. Therefore, this manual procedure entails subjectivity and variability in the IMT evaluation. Instead, this article suggests a fully automatic segmentation technique for ultrasound images of the common carotid artery. The proposed methodology is based on machine learning and artificial neural networks for the recognition of IMT intensity patterns in the images. For this purpose, a deep learning strategy has been developed to obtain abstract and efficient data representations by means of auto-encoders with multiple hidden layers. In particular, the considered deep architecture has been designed under the concept of extreme learning machine (ELM). The correct identification of the arterial layers is achieved in a totally user-independent and repeatable manner, which not only improves the IMT measurement in daily clinical practice but also facilitates the clinical research. A database consisting of 67 ultrasound images has been used in the validation of the suggested system, in which the resulting automatic contours for each image have been compared with the average of four manual segmentations performed by two different observers (ground-truth). Specifically, the IMT measured by the proposed algorithm is 0.625 ± 0.167 mm (mean ± standard deviation), whereas the corresponding ground-truth value is 0.619 ± 0.176 mm. Thus, our method shows a difference between automatic and manual measures of only 5.79 ± 34.42 μm. Furthermore, different quantitative evaluations reported in this paper indicate that this procedure outperforms other methods presented in the literature.     

A driving simulator study to explore the effects of text size on the visual demand of in-vehicle displays

Modern vehicles increasingly utilise a large display within the centre console, often with touchscreen capability, to enable access to a wide range of driving and non-driving-related functionality. The text provided on such displays can vary considerably in size, yet little is known about the effects of different text dimensions on how drivers visually sample the interface while driving and the potential implications for driving performance and user acceptance. A study is described in which sixteen people drove motorway routes in a medium-fidelity simulator and were asked to read text of varying sizes (9 mm, 8 mm, 6.5 mm, 5 mm, or 4 mm) from a central in-vehicle display. Pseudo-text was used as a stimulus to ensure that participants scanned the text in a consistent fashion that was unaffected by comprehension. There was no evidence of an effect of text size on the total time spent glancing at the display, but significant differences arose regarding how glances were distributed. Specifically, larger text sizes were associated with a high number of relatively short glances, whereas smaller text led to a smaller number of long glances. No differences were found in driving performance measures (speed, lateral lane position). Drivers overwhelmingly preferred the ‘compromise’ text sizes (6.5 mm and 8 mm). Results are discussed in relation to the development of large touchscreens within vehicles.     

Wavelet based shock wave and muzzle blast classification for different supersonic projectiles

The article presents a pattern recognition approach to acoustic shock wave and muzzle blast detection. Gunshot signatures are divided into multiple classes, given by combination of 3 types of supersonic weapons of different caliber: 7.62 mm, 5.56 mm and 9 mm and 3 types of acoustic events: shock wave, muzzle blast and reflections. The classification is performed on wavelet compressed 100 μs time frames. The experiment shows that the choice of a fitting wavelet base is crucial for the quality of recognition.     

Unsupervised feature selection using swarm intelligence and consensus clustering for automatic fault detection and diagnosis in Heating Ventilation and Air Conditioning systems

Various sensory and control signals in a Heating Ventilation and Air Conditioning (HVAC) system are closely interrelated which give rise to severe redundancies between original signals. These redundancies may cripple the generalization capability of an automatic fault detection and diagnosis (AFDD) algorithm. This paper proposes an unsupervised feature selection approach and its application to AFDD in a HVAC system. Using Ensemble Rapid Centroid Estimation (ERCE), the important features are automatically selected from original measurements based on the relative entropy between the low- and high-frequency features. The materials used is the experimental HVAC fault data from the ASHRAE-1312-RP datasets containing a total of 49 days of various types of faults and corresponding severity. The features selected using ERCE (Median normalized mutual information (NMI) = 0.019) achieved the least redundancies compared to those selected using manual selection (Median NMI = 0.0199) Complete Linkage (Median NMI = 0.1305), Evidence Accumulation K-means (Median NMI = 0.04) and Weighted Evidence Accumulation K-means (Median NMI = 0.048). The effectiveness of the feature selection method is further investigated using two well-established time-sequence classification algorithms: (a) Nonlinear Auto-Regressive Neural Network with eXogenous inputs and distributed time delays (NARX-TDNN); and (b) Hidden Markov Models (HMM); where weighted average sensitivity and specificity of: (a) higher than 99% and 96% for NARX-TDNN; and (b) higher than 98% and 86% for HMM is observed. The proposed feature selection algorithm could potentially be applied to other model-based systems to improve the fault detection performance.     

Improved digital photogrammetry technique for crack monitoring

Inspections to evaluate the safety, durability, and service life of aging infrastructure play an important role in determining the countermeasures that need to be taken, such as reinforcement, repair, and reconstruction. In infrastructure containing concrete, such as bridges and tunnels, crack widths and patterns on surfaces are two of the most important signs used to estimate durability. Current conventional techniques used for this purpose suffer from challenges such as tediousness, subjectivity, and high cost. Consequently, a new measurement technique that overcomes these challenges while measuring crack displacement with high accuracy and precision in aging civil engineering structures is needed. In this paper, we proposed a technique for measuring crack displacement using a digital camera image. In the proposed technique, reflective targets are established around both sides of a crack as gauges, and subsequent digital camera images of the targets are subjected to image processing to determine the displacements of the targets. These displacements can be measured using images captured from any arbitrary camera position. The results of experiments conducted to verify the efficacy of the proposed method show that crack displacements of less than 0.10 mm can be measured with high accuracy and precision using digital images captured at a distance of 10.0 m from the target, while less than 0.20 mm changes in the tensile displacement of the crack can be measured from an image captured at 25.0 m from the crack. Measurement results obtained from a tunnel are also presented to show that cracks in the walls of an actual tunnel can be identified through simple measurements. These measurements, taken over a period of one year, indicate that the tendency of crack displacement and slide movements are in close agreement.     

Piezoelectric unimorph valve assembled on an LTCC substrate

In this paper a piezoelectric initially open valve was designed in low temperature co-fired ceramic (LTCC), manufactured using standard processes, and tested with integrated gas channels inside the LTCC module. Actuation of the valve was based on a piezoelectric unimorph with a diameter of 15 mm and thickness of 0.35 mm glued onto the fired LTCC substrate. Subsequently, a series of tests, including flow, displacement and switching time measurements, was carried out. Measurements of the valve revealed a flow of 143 ml/min under 1 bar pressure, leakage levels of 4%, valve displacement of 1.3 μm, and closing times less than 30 ms. Additional miniaturization and integration of an embedded valve in the LTCC will be pursued, enabling improved manufacturing as a batch process and micro- and nano-litre fluid management for various applications.     

Extension of a hybrid thermal LBE scheme for large-eddy simulations of turbulent convective flows

Following the work of Lallemand and Luo [Lallemand P, Luo L-S. Theory of the lattice Boltzmann method: acoustic and thermal properties in two and three dimensions. Phys Rev E 2003;68:036706] we validate, apply and extend the hybrid thermal lattice Boltzmann scheme (HTLBE) by a large-eddy approach to simulate turbulent convective flows. For the mass and momentum equations, a multiple-relaxation-time LBE scheme is used while the heat equation is solved numerically by a finite difference scheme. We extend the hybrid model by a Smagorinsky subgrid scale model for both the fluid flow and the heat flux. Validation studies are presented for laminar and turbulent natural convection in a cavity at various Rayleigh numbers up to 5 × 10¹⁰ for Pr = 0.71 using a serial code in 2D and a parallel code in 3D, respectively. Correlations of the Nusselt number are discussed and compared to benchmark data. As an application we simulated forced convection in a building with inner courtyard at Re = 50 000.     

Empirical modeling of splitting tensile strength from cylinder compressive strength of concrete by genetic programming

Compressive strength and splitting tensile strength are both mechanical properties of concrete that are utilized in structural design. This study presents gene expression programming (GEP) as a new tool for the formulations of splitting tensile strength from compressive strength of concrete. For purpose of building the GEP-based formulations, 536 experimental data have been gathered from existing literature. The GEP-based formulations are developed for splitting tensile strength of concrete as a function of age of specimen and cylinder compressive strength. In experimental parts of this study, cylindrical specimens of 150 × 300 mm and 100 × 200 mm in dimensions are utilized. Training and testing sets of the GEP-based formulations are randomly separated from the complete experimental data. The GEP-based formulations are also validated with additional 173 data of experimental results other than the data used in training and testing sets of the GEP-based formulations. All of the results obtained from the GEP-based formulations are compared with the results obtained from experimental data, the developed regression-based formulation and formulas given by some national building codes. These comparisons showed that the GEP-based formulations appeared to well agree with the experimental data and found to be quite reliable.     

Theoretical predictions and experimental validations on machining the Nimonic C-263 super alloy

The current paper presents the simulated 3D Finite Element Model (FEM) and experimental validation while turning the Nimonic C-263 super alloy using a cemented carbide cutting tool. FEM machining simulations was carried out using a Lagrangian finite element based machining model to predict the tangential cutting force, temperature distribution at tool tip and the effective stress and strain. All simulations were performed according to the cutting conditions designed, using the orthogonal array. The work piece was considered as perfectly plastic and its shape was taken as a curved model. An experimental validation of the cutting process was conducted in order to verify the simulated results of tangential cutting force and temperature at tool tip and the comparison shows that the percentage error 6% was observed and the shear friction factor 0.6 indicates good agreement between the simulated results and the experiment results. As the cutting speed is increased from 22 m/min to 54 m/min at higher feed rate, a larger strain to an extent of up to 6.55 mm/mm, a maximum value of 810 MPa stress and higher temperature localization to an extent of 620 °C at tool tip were observed.     

Modified Köhler illumination for LED-based projection display

Common projection optics use Köhler illumination to achieve a required lighting. These systems always prevent the realization of a compact optical configuration along with a high lumen output. Based on conventional Köhler illumination, a modified Köhler illumination system for LED-based projection display is presented in this paper, which can significantly reduce the system volume while allowing for adequate and homogeneous illumination. Equipped with the proposed system, a pocket-sized CF-LCoS projector with a physical dimension of 27.4 mm × 19.4 mm × 9.6 mm is designed, simulated and analyzed. Compared to conventional approaches, this design could offer an average 43% volume reduction with acceptable tolerance. To the best of our knowledge, the screen uniformity of 90.2% and the light efficiency of 56.5% are competitive as compared with those of the currently commercialized pocket-sized CF-LCoS projectors.     

Compound Linguistic Scale

Rating scales are the essential interfaces for many research areas such as in decision making and recommendation. Some issues concerning syntactic and sematic structures are still open to discuss. This research proposes a Compound Linguistic Scale (CLS), a two dimension rating scale, as a promising rating interface. The CLS is comprised of Compound Linguistic Variable (CLV) and Deductive Rating Strategy (DRS). CLV can ideally produce 21 to 73 ((7 ± 2)((7 ± 2) − 1) + 1) ordinal-in-ordinal rating items, which extends the classic rating scales usually on the basis of 7 ± 2 principle, to better reflect the raters’ preferences whilst DRS is a double step rating approach for a rater to choose a compound linguistic term among two dimensional options on a dynamic rating interface. The numerical analyses show that the proposed CLS can address rating dilemma for a single rater and more accurately reflects consistency among various raters. CLS can be applied to surveys, questionnaires, psychometrics, recommender systems and decision analysis of various application domains.     

Electroactive polymer based microfluidic pump

A planar, valveless, microfluidic pump using electrostrictive poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] based polymer as the actuator material is presented. P(VDF-TrFE) thick films having a large electrostrictive strain ∼5–7% and high elastic energy density of 1 J/cm³ have been used in a unimorph diaphragm actuator configuration. The microfluidic pump was realized by integrating a nozzle/diffuser type fluidic mechanical-diode structure with the polymer microactuator. The P(VDF-TrFE) unimorph diaphragm actuator, 80 μm thick and 2.2 mm × 2.2 mm in lateral dimensions, showed an actuation deflection of 80 μm for an applied electric field of 90 MV/m. The microfluidic pump could pump methanol at a flow rate of 25 μl/min at 63 Hz with a backpressure of 350 Pa. The flow rate of this pump could be easily controlled by external electrical field. Two different sizes of nozzle/diffuser elements were studied and the pumping efficiency of these structures is 11 and 16%, respectively.     

Development of new shoe sizing system for women based on regression analysis of foot shapes

This study aims to demonstrate a new method of developing a shoe sizing system with a standard fitting for each size for Bangladeshi women based on foot measurements. In this study, bivariate correlation analysis was carried out to determine key foot dimensions of 976 women aged 20 to 60. Simple linear regression analyses of key parameters against foot length (FL) were conducted, and the regression equations assisted in determining grading value and size-fit combinations. Nine sizes with three fittings (narrow, standard, and wide) each were generated where the grading values were 6 mm, 5 mm, 2 mm, and 4 mm for FL, joint girth (JG), joint width (JW), and arch length (AL), respectively. Cross-tabulation analysis verified the sizing system with a coverage rate 94.98% of JG, 88.02% of JW, and 98.77% of AL, where standard fittings covered the maximum number of participants. This study could benefit women in choosing accurate shoe sizes for their feet to ensure proper shoe fitting.Relevance to industryThe proposed new shoe sizing system could assist the footwear industries in manufacturing women's shoes in different sizes with appropriate sizing and grading values, which will provide better fitting than existing systems. In addition, industries could produce shoes with a smaller number of size-fit combinations to accommodate most women's feet.     

A decision support system based on fuzzy reasoning and AHP–FPP for the ecodesign of products: Application to footwear as case study

The design stage represents one of the most critic steps for product development. Here, a great number of considerations have to be borne in mind, e.g., technical, functional, aesthetic or economic criteria. More recently, the increasing concerns on environmental aspects have added complexity to the process, known as ecodesign. In this respect, a framework to integrate the criteria provided by quantitative environmental indicators has been proposed on the basis of Fuzzy Preference Programming method features and fuzzy logic reasoning. As a result, an integrated Ecodesign Index (EcoInd) is obtained. This idea enables the decision making at process and product level taking into account different indicators at a time. The ecodesign of children's footwear was taken as case study and an ecodesign tool (decision support system) that included the estimation of environmental indicators and their integration was developed. Different models of shoes were analyzed to identify the most environmentally friendly design and to test the tool. In this case, the Ecological Footprint and two Environmental Risk Assessment indicators, namely Hazard Quotient and Cancer Risk, were selected as relevant environmental indicators and they were computed from data provided by a shoes manufacturer. Then, these indicators were integrated in the ecodesign tool and the EcoInd values were appraised for the children's footwear models analyzed. According to these figures, they were ranked as Red Leather > White Leather > White Synthetic > Pink Synthetic, from best to worst.     

Facile synthesis of lanthanide vanadates and their luminescent properties

GdVO₄:Eu³⁺, Bi³⁺ with tetragonal phase has been successfully synthesized by employing efficient irradiations. The assembly of composites with fine grains based on acoustic energy and microwave radiation requires low temperature (90 °C) and short reaction time (60 min). All the compounds exhibited red emissions and they can be sensitized through the doped Bi³⁺ ions. The dependence of pH changes and doping concentration on the fluorescence features has been discussed. The photoluminescence measurements show that the optical properties achieved the best results at pH = 9 for GdVO₄:Eu³⁺(5 mol%), Bi³⁺(1 mol%) or pH = 7 for GdVO₄:Eu³⁺.     

Micromachined quartz resonator based infrared detector array

We report the fabrication and performance of a micromachined Y-cut quartz resonator based thermal infrared detector array. 1 mm diameter and 18 μm thick (90 MHz) inverted mesa configuration quartz resonator arrays with excellent resonance characteristics have been fabricated by RIE etching of quartz. Temperature sensitivity of 7.2 kHz/K was experimentally measured. Infrared calibration tests on the resonator array even without the use of infrared absorbers gave a responsivity of 14.3 MHz/W and an NEP of 326 nW. In this first report on the performance of the Y-cut quartz resonator infrared thermal detector array, the response time measurements were found to be limited by the slow measurement time of the impedance scans and the undesired heating of the quartz substrate. Most importantly, this initial work demonstrates the possibility of realizing infrared detector arrays for room temperature thermal imaging applications that can rival current state of the art in the field.