Practical Design Considerations Research Articles

Substrate Integrated Waveguide Filters: Practical Aspects and Design Considerations

In the current literature, the majority of research work reported on substrate integrated waveguide (SIW) filters has focused on the development of physical topologies as well as design and realization techniques for filter specifications and electrical parameters. The practical and successful implementation of SIW filters requires special consideration of mechanical and thermal properties during the design and processing stages. These properties include the effects of ambient operating environment, average, and peak power-handling capabilities as well as design and production economics, including labor costs, skilled labor availability, mass-production issues, and projected production delivery rates [1]. Bandpass filters are more concerned with those practical aspects as their in-band and out-of-band performance are much more sensitive than other types of filters to those mechanical and thermal issues.

Flying spot laser triangulation scanner using lateral synchronization for surface profile precision measurement.

High-speed surface profile measurement with high precision is crucial for target inspection and quality control. In this study, a laser scanner based on a single point laser triangulation displacement sensor and a high-speed rotating polygon mirror is proposed. The autosynchronized scanning scheme is introduced to alleviate the trade-off between the field of view and the range precision, which is the inherent deficiency of the conventional triangulation. The lateral synchronized flying spot technology has excellent characteristics, such as programmable and larger field of view, high immunity to ambient light or secondary reflections, high optical signal-to-noise ratio, and minimum shadow effect. Owing to automatic point-to-point laser power control, high accuracy and superior data quality are possible when measuring objects featuring varying surface characteristics even in demanding applications. The proposed laser triangulation scanner is validated using a laboratory-built prototype and practical considerations for design and implementation of the system are described, including speckle noise reduction method and real-time signal processing. A method for rapid and accurate calibration of the laser triangulation scanner using lookup tables is also devised, and the system calibration accuracy is generally smaller than ±0.025 mm. Experimental results are presented and show a broad application prospect for fast surface profile precision measurement.

Movers and shakers

Numerous energy harvesting wireless devices that will serve as building blocks for the Internet of Things (IoT) are currently under development. However, there is still only limited understanding of the properties of various energy sources and their impact on energy harvesting adaptive algorithms. Hence, we focus on characterizing the kinetic (motion) energy that can be harvested by a wireless node with an IoT form factor and on developing energy allocation algorithms for such nodes. In this paper, we describe methods for estimating harvested energy from acceleration traces. To characterize the energy availability associated with specific human activities (e.g., relaxing, walking, cycling), we analyze a motion dataset with over 40 participants. Based on acceleration measurements that we collected for over 200 hours, we study energy generation processes associated with day-long human routines. We also briefly summarize our experiments with moving objects. We develop energy allocation algorithms that take into account practical IoT node design considerations, and evaluate the algorithms using the collected measurements. Our observations provide insights into the design of motion energy harvesters, IoT nodes, and energy harvesting adaptive algorithms.

Considerations for test design to accommodate energy‐budget models in ecotoxicology: A case study for acetone in the pond snail Lymnaea stagnalis

Toxicokinetic-toxicodynamic (TKTD) modeling offers many advantages in the analysis of ecotoxicity test data. Calibration of TKTD models, however, places different demands on test design compared with classical concentration-response approaches. In the present study, useful complementary information is provided regarding test design for TKTD modeling. A case study is presented for the pond snail Lymnaea stagnalis exposed to the narcotic compound acetone, in which the data on all endpoints were analyzed together using a relatively simple TKTD model called DEBkiss. Furthermore, the influence of the data used for calibration on accuracy and precision of model parameters is discussed. The DEBkiss model described toxic effects on survival, growth, and reproduction over time well, within a single integrated analysis. Regarding the parameter estimates (e.g., no-effect concentration), precision rather than accuracy was affected depending on which data set was used for model calibration. In addition, the present study shows that the intrinsic sensitivity of snails to acetone stays the same across different life stages, including the embryonic stage. In fact, the data on egg development allowed for selection of a unique metabolic mode of action for the toxicant. Practical and theoretical considerations for test design to accommodate TKTD modeling are discussed in the hope that this information will aid other researchers to make the best possible use of their test animals.

Optimal Configuration Design for the Variable Geometry Wing-Box

In wing morphing, it is desirable to have a system that acts both as a load-bearing structure and a morphing mechanism, without any distinction between the two. When dealing with a rather large design space, designing for this requirement would be less challenging because the constituting structural elements could be topologically placed in a fashion to enhance the static characteristics of the system, without sacrificing its kinematic abilities. However, in the case of an aircraft wing, where the design space is highly restrictive, conventional approaches typically yield inefficient designs from a static perspective. Such restrictions have served as inspirations for the proposed concept of a reconfigurable system, which is able to alter its kinematic and static characteristics to act both as a mechanism and a high-stiffness structure. The optimal configuration design of this system, referred to as the variable geometry wing-box is discussed in this paper. The optimal configuration design problem is posed in two parts: 1) the optimal limb configuration, and 2) the optimal topological configuration. The former seeks the optimal design of the kinematic joints and links, while the latter seeks the minimal compliance solution to their placement within the design space. In addition to the static and kinematic criteria required for reconfigurability, practical design considerations such as fail-safe requirements and design for minimal aeroelastic impact are included as constraints in the optimization process. In the end, the optimal configuration for the variable geometry wing-box is presented, and its rigidity is validated using a reconfigurable prototype.

Practical Design Considerations for Large PM Machines

To help machine designers to design large permanent magnet (PM) machines to be more accurate, this paper presents a set of design considerations that are very often ignored by machine designers. These considerations are categorized into several aspects: electromagnetic (EM) performance, losses and efficiency, fault and stability, and some other issues. The effects of various practical factors are presented and some corresponding design methods are introduced.

Discovery and Development of DNA Methylation-Based Biomarkers for Lung Cancer

Lung cancer remains the primary cause of cancer-related deaths worldwide. Improved tools for early detection and therapeutic stratification would be expected to increase the survival rate for this disease. Alterations in the molecular pathways that drive lung cancer, which include epigenetic modifications, may provide biomarkers to help address this major unmet clinical need. Epigenetic changes, which are defined as heritable changes in gene expression that do not alter the primary DNA sequence, are one of the hallmarks of cancer, and prevalent in all types of cancer. These modifications represent a rich source of biomarkers that have the potential to be implemented in clinical practice. This perspective describes recent advances in the discovery of epigenetic biomarkers in lung cancer, specifically those that result in the methylation of DNA at CpG sites. We discuss one approach for methylation-based biomarker assay development that describes the discovery at a genome-scale level, which addresses some of the practical considerations for design of assays that can be implemented in the clinic. We emphasize that an integrated technological approach will enable the development of clinically useful DNA methylation-based biomarker assays. While this article focuses on current literature and primary research findings in lung cancer, the principles we describe here apply to the discovery and development of epigenetic biomarkers for other types of cancer.

DL Seng-Pan U Visits SSCS-Beijing on 6 May: Talks at IMETU, the Institute of Microelectronics of Tsinghua University, About IC Design Trends [Chapters

Summary form only given, as follows. The evolving broadband wireless communication increasingly drives fast development on high-performance consumer portable smart and green gadgets with longer battery life, which leads to growing demands on ADCs with higher energy efficiency. SAR-type ADCs which take advantages of CMOS technology downscaling for their "highly digital" implementation have been dominating large segments of high-speed and energy efficient ADCs with efficiencies down to fJ!conversion step at 100MHz+ sampling rate. This talk provides firstly an overview of the state-of-the-art high energy efficient ADCs, and then present the trends of the ADCs through the energy, speed and noise Analysis for various architectures including SAR & Binary-Search, Multi-bit SAR, Flash SAR and Pipeline SAR. Some practical design considerations will be also addressed.

Thermal expansion recovery microscopy: Practical design considerations

A detailed study of relevant parameters for the design and operation of a photothermal microscope technique recently introduced is presented. The technique, named thermal expansion recovery microscopy (ThERM) relies in the measurement of the defocusing introduced by a surface that expands and recovers upon the heating from a modulated source. A new two lens design is presented that can be easily adapted to commercial infinite conjugate microscopes and the sensitivity to misalignment is analyzed. The way to determine the beam size by means of a focus scan and the use of that same scan to verify if a thermoreflectance signal is overlapping with the desired ThERM mechanism are discussed. Finally, a method to cancel the thermoreflectance signal by an adequate choice of a nanometric coating is presented.

An LLC Resonant DC–DC Converter for Wide Output Voltage Range Battery Charging Applications

In this paper, resonant tank design procedure and practical design considerations are presented for a high performance LLC multiresonant dc-dc converter in a two-stage smart battery charger for neighborhood electric vehicle applications. The multiresonant converter has been analyzed and its performance characteristics are presented. It eliminates both low- and high-frequency current ripple on the battery, thus maximizing battery life without penalizing the volume of the charger. Simulation and experimental results are presented for a prototype unit converting 390 V from the input dc link to an output voltage range of 48-72 V dc at 650 W. The prototype achieves a peak efficiency of 96%.

Material selection for a constructed wetroof receiving pre-treated high strength domestic wastewater

A constructed wetroof (CWR) is defined in this study as the combination of a green roof and a constructed wetland: a shallow wastewater treatment system placed on the roof of a building. The foremost challenge of such CWRs, and the main aim of this investigation, is the selection of an appropriate matrix capable of assuring the required hydraulic retention time, the long-term stability and the roof load-bearing capacity. Six substrata were subjected to water dynamics and destructive tests in two testing-tables. Among all the materials tested, the substratum configuration composed of sand, light expanded clay aggregates, biodegradable polylactic acid beads together with stabilization plates and a turf mat is capable of retaining the water for approximately 3.8 days and of providing stability (stabilization plates) and an immediate protection (turf mat) to the system. Based on those results, a full-scale CWR was built, which did not show any physical deterioration after 1 year of operation. Preliminary wastewater treatment results on the full-scale CWR suggest that it can highly remove main wastewater pollutants (e.g. chemical oxygen demand, PO4(3-)-P and NH4(+)-N). The results of these tests and practical design considerations of the CWR are discussed in this paper.

Model-based selection of full-scale Wells turbines for ocean wave energy conversion and prediction of their aerodynamic and acoustic performances

One of the most intensively studied principles of harnessing the energy from ocean waves is the oscillating water column device. The oscillating water column converts the motion of the water waves into a bi-directional airflow, which in turn drives an air turbine. The bi-directional axial Wells turbine as a candidate for oscillating water column power take-off systems was the object of considerable research conducted in the last decades. However, there is a lack of consistent data to support practical design considerations when pre-selecting a turbine for an oscillating water column power plant. Furthermore, to minimize the overall environmental impact of this technology requires the assessment of the aero-acoustic noise associated with a Wells turbine’s operation. The effect of cascade solidity and hub-to-tip ratio on the aero-acoustic performance of Wells turbine rotors is assessed systematically by numerical simulations and model scale testing. Based on the data from the study on these generic design parameters, new Wells turbine design charts were developed. For a given plant site, main machine dimensions are identified and a time domain model is used to predict the annual energy output and the annual equivalent sound power level. Maximum values of total-static peak efficiency and low sound emission can be achieved by selecting moderate values of cascade solidity and hub-to-tip ratio. On the other hand, high hub-to-tip ratio rotors in combination with high solidity are recommended for a maximum range of operation without stall, as the pressure head is varied. The designer of an oscillating water column system usually specifies selected operating conditions on dimensional turbine characteristics. Combinations of suitable rotor diameter and rotational speeds are selected using the design chart approach. When a fully operating, full-scale Wells turbine at fixed speed is assessed, higher cascade solidity maximizes the annual energy output at minimum acoustic emission. The drawback is a slightly larger rotor diameter when, e.g. compared with a lower cascade solidity.

Q Selection for an electro-optical earth imaging system: theoretical and experimental results

This paper explores practical design considerations for selecting Q for an electro-optical earth imaging system, where Q is defined as (λ FN) / pixel pitch. Analytical methods are used to show that, under imaging conditions with high SNR, increasing Q with fixed aperture cannot lead to degradation of image quality regardless of the angular smear rate of the system. The potential for degradation of image quality under low SNR is bounded by an increase of the detector noise scaling as Q. An imaging test bed is used to collect representative imagery for various Q configurations. The test bed includes real world errors such as image smear and haze. The value of Q is varied by changing the focal length of the imaging system. Imagery is presented over a broad range of parameters.

On the nonlinear on–off dynamics of a butterfly valve actuated by an induced electromotive force

In this paper, we study the nonlinear dynamics of a butterfly valve actuated by the induced electromotive force (emf) of a permanent magnet, with a focus on the on–off dynamics of the valve and its nonlinear response under ambient perturbation. The complex interplay between the electromagnetic, hydrodynamic and mechanical forces leads to a fundamentally multiphysical, nonlinear dynamical model for the problem. First, we analyze the stability of the on–off conditions in terms of three critical dynamical parameters – the actuating DC voltage, inlet velocity and the opening angle. Next, the response of the system to perturbations around the equilibrium points is studied in terms of the frequency response using the method of multiple scales. Finally, evidence of fractality is established using Melnikov analysis and a plot of the basins of attraction. The results reported in the article, in addition to being of fundamental theoretical interest, are expected to impact practical design considerations of electromechanical butterfly valves.

Specifications of a continual reassessment method design for phase I trials of combined drugs

In studies of combinations of agents in phase I oncology trials, the dose-toxicity relationship may not be monotone for all combinations, in which case the toxicity probabilities follow a partial order. The continual reassessment method for partial orders (PO-CRM) is a design for phase I trials of combinations that leans upon identifying possible complete orders associated with the partial order. This article addresses some practical design considerations not previously undertaken when describing the PO-CRM. We describe an approach in choosing a proper subset of possible orderings, formulated according to the known toxicity relationships within a matrix of combination therapies. Other design issues, such as working model selection and stopping rules, are also discussed. We demonstrate the practical ability of PO-CRM as a phase I design for combinations through its use in a recent trial designed at the University of Virginia Cancer Center.

Practical Design and Implementation Considerations of a Computer Adaptive Foreign Language Test

While the psychometric and statistical models underlying the design of computer adaptive tests (CAT) are well understood, relatively few working models exist for the purpose of foreign language assessment. Likewise, little has been published concerning the practical considerations affecting the implementation of such tests. in the process of constructing the Monash/Melbourne French CAT, we discovered much about putting testing theory into practice. The present paper reports this experience in three parts. In a preliminary section, we describe the academic context in which the French CAT was created and trialed. This is followed by a detailed consideration of the test presentation platform and operating algorithms. Lastly, we give an evaluation of the first administration of the French CAT, accompanied by a discussion of the test's reliability and validity as a placement instrument for first year Australian university students.

Practical Design Considerations for Contactless Power Transfer Quadrature Pick-Ups

This paper presents a practical prototype of a recent multiphase (quadrature) pick-up suited for contactless power transfer systems. The investigation is based on a commercial pick-up design for automatic guided vehicle systems and is evaluated in terms of its ability to extend the allowable tolerance of this pick-up receiver to the track while achieving the desired output power profile with good efficiency, without compromising normal operation. Practical aspects of the design are discussed along with means by which magnetic design and electronic compensation can be used to improve performance.

Context and repetition in word learning.

Young children learn words from a variety of situations, including shared storybook reading. A recent study by Horst et al. (2011a) demonstrates that children learned more new words during shared storybook reading if they were read the same stories repeatedly than if they were read different stories that had the same number of target words. The current paper reviews this study and further examines the effect of contextual repetition on children's word learning in both shared storybook reading and other situations, including fast mapping by mutual exclusivity. The studies reviewed here suggest that the same cognitive mechanisms support word learning in a variety of situations. Both practical considerations for experimental design and directions for future research are discussed.

Design of radial reinforcement for prestressed concrete containments

Nuclear containments are critical components for safety of nuclear power plants. Failure can result in catastrophic safety consequences as a result of leakage of radiation. Prestressed concrete containments have been used in large nuclear power plants with significant design internal pressure. These containments are generally reinforced with prestressing tendons in the circumferential (hoop) and meridional (vertical) directions. The curvature effect of the tendons introduces radial tensile stresses in the concrete shell which are generally neglected in the design of such structures. It is assumed that such tensile radial stresses are small as such no radial reinforcement is provided for this purpose. But recent instances of significant delaminations in Crystal River Unit 3 in Florida have elevated the need for reevaluation of the radial tension issue in prestressed containment. Note that currently there are no well accepted industry standards for design and detailing of radial reinforcement. This paper discusses the issue of radial tension in prestressed cylindrical and dome shaped structures and proposes formulae to calculate radial stresses. A practical example is presented to illustrate the use of the proposed method which is then verified by using state of art finite element analysis. This paper also provides some practical design consideration for detailing of radial reinforcement in prestressed containments.

Theoretical Analysis and Practical Considerations for the Integrated Time-Stretching System Using Dispersive Delay Line (DDL)

In this paper, we perform the theoretical analysis and experimental demonstration of an on-chip implementation of a Ku-band nanosecond scale time-stretching (TS) system in a 130-nm IBM 8RF CMOS process. The theory of the TS system is applicable to general TS systems. In this study, we explain the impact of the time-bandwidth product (TBP) on practical design considerations and derive the error and distortion of a general TS system based on a dispersive delay line with perfect linear group delay and all pass amplitude characteristic. We also derive the time resolution of a general TS system using both the principle of uncertainty as well as the short time Fourier transform method. This fundamental result enables a designer to understand the qualitative relationship between the TBP and the best possible resolution of the TS system. Finally, we experimentally demonstrate the TS system on chip with nanosecond group-delay variance and 12-16-GHz bandwidth. This demonstration indicates the potential for implementation of more complicated time-scaling signal-processing systems on chip, as well as a quantification of the error and distortion for such systems.