Practical Design Considerations Research Articles

Exploring the Design of mHealth Systems for Health Behavior Change using Mobile Biosensors

A person’s health behavior plays a vital role in mitigating their risk of disease and promoting positive health outcomes. In recent years, mHealth systems have emerged to offer novel approaches for encouraging and supporting users in changing their health behavior. Mobile biosensors represent a promising technology in this regard; that is, sensors that collect physiological data (e.g., heart rate, respiration, skin conductance) that individuals wear, carry, or access during their normal daily activities. mHealth system designers have started to use the health information from physiological data to deliver behavior-change interventions. However, little research provides guidance about how one can design mHealth systems to use mobile biosensors for health behavior change. In order to address this research gap, we conducted an exploratory study. Following a hybrid approach that combines deductive and inductive reasoning, we integrated a body of fragmented literature and conducted 30 semi-structured interviews with mHealth stakeholders. From this study, we developed a theoretical framework and six general design guidelines that shed light on the theoretical pathways for how the mHealth interface can facilitate behavior change and provide practical design considerations.

Spatio-Temporal Impact of Hand and Body Blockage for Millimeter-Wave User Equipment Design at 28 GHz

The recently proposed channel model by the Third Generation Partnership Project for fifth generation New Radio (5G-NR) systems at millimeter- wave carrier frequencies in TR38.901 provides a good starting point for understanding the impact of propagation, material penetration, and blockage in cellular access systems. With this backdrop, the focus of this article is on hand and body blockage which have a significant bearing on user equipment (UE) design and in the practical viability of millimeter-wave systems. Building on TR38.901, we first study hand and body blockage loss with experiments using a 28 GHz experimental prototype that emulates a 5G base station and a form-factor UE. These measurement estimates show that while blockage losses can be substantial, they are significantly lower than the agreed model in TR38.901. We then study the implications of these revised estimates on spherical coverage with the UE. For this, we consider two form-factor UE designs: a face design and an edge design. Our studies show that while both designs are generally comparable in terms of spherical coverage, practical design considerations favor the edge design over the face design. We finally report on the timescales at which blockage events occur and show that given the symbol periods in 5G-NR, it is possible to implement mitigation strategies to overcome blockage (e.g., switch beams at the UE from a blocked path to an unblocked path).

Enhancing landscape connectivity through multifunctional green infrastructure corridor modeling and design

Landscape connectivity is critical for ecosystem health and biodiversity conservation, yet urbanization is increasing habitat fragmentation. Green corridors that connect isolated remnant habitat patches (e.g. parks) can increase connectivity and provide ecosystem services in cities. Vacant land, especially prevalent in shrinking cities, presents a unique opportunity to reconnect these landscapes. This paper provides a practical and replicable approach for assessing landscape connectivity patterns and identifying priority locations for green corridors. The methodology integrates social and ecological factors coupled with site-scale multifunctional greenway designs and is applied to the city of Detroit as a proof of concept. First, we use FRAGSTATS to evaluate structural landscape connectivity patterns at a census tract scale. A functional connectivity assessment based on graph theory and Conefor software is used to validate the results, which indicate that habitat is highly fragmented in Detroit. To identify opportunities to reduce this fragmentation, we use a least-cost path approach to map potential green corridors linking city parks through vacant parcels, alleys, and smaller green spaces, and prioritize these corridors using a gravity model and network analysis. To make the model more concrete and useful for decision-makers, we develop site-level multifunctional corridor design typologies. This study presents a novel approach to assessing urban connectivity and a multi-scalar, systematic methodology for planning urban green infrastructure networks that connects landscape ecology with practical planning and design considerations to maximize social and ecological functions.

Spray congealing: a versatile technology for advanced drug-delivery systems.

Spray congealing is a low cost, simple and versatile method to produce microparticles without the use of organic or aqueous solvent. This review provides a detailed picture of the pharmaceutical applications of this technology, with an overview of the spray-congealed-based drug-delivery systems. First, the basic principles and equipment of spray congealing technology are presented. Then, representative examples of the drug-delivery systems are examined and critically discussed. Emphasis is given on the role of formulation variables, together with practical considerations for formulation design. In addition, the current status of the industrial applications of this technology within the pharmaceutical field is examined. The final part points out benefits, limitations and future perspectives of this technology in drug delivery.

Design and Analysis of Piezoelectric Metamaterial Beams With Synthetic Impedance Shunt Circuits

We present an electromechanical modeling framework and a detailed numerical investigation for the design and analysis of piezoelectric metamaterial beams whose unit cells with segmented electrode pairs are shunted to synthetic impedance circuits. This framework aims to extend the well-studied locally resonant piezoelectric metamaterials and resulting finite metastructures with specified boundary conditions to novel concepts beyond bandgaps associated with simple inductive shunts. Overcoming the bandgap limitations of the locally resonant design requires more advanced considerations in the electrical domain. To this end, we bridge piezoelectric metamaterials and synthetic impedance shunts, and present a general design and analysis framework along with numerical case studies. A general procedure is implemented based on the root locus method for choosing the shunt circuit impedance, with an emphasis on vibration attenuation and practical design considerations. Case studies are presented for systems with locally resonant bandgaps with or without negative capacitance, as well as systems with multiple distinct bandgaps, and the necessary shunt admittance is derived for each case. Simulations are performed for a typical finite meta material beam with synthetic impedance shunts, accounting for the finite sampling rate and circuit dynamics. Time-domain simulations using these synthetic impedance circuits are compared to the ideal frequency-domain results with very good agreement.

Deflection behavior of a prestressed concrete beam reinforced with carbon fibers at elevated temperatures

Fiber reinforced polymer(FRP) have unique advantages like high strength to weight ratio, excellent corrosion resistance, improving deformability and cost effectiveness. These advantages have gained wide acceptance in civil engineering applications. FRP tendons for prestressing applications are emerging as one of the most promising technologies in the civil engineering industry. However, the behavior of such members under the influence of elevated temperatures is still unknown. The knowledge and application of this could lead to a cost effective and practical considerations in fire safety design. Therefore, this study examines the deflection behavior of the carbon fiber reinforced polymer(CFRP) prestressed concrete beam at elevated temperatures. In this article, an analytical model is developed which integrates the temperature dependent changes of effective modulus of FRP in predicting the deflection behavior of CFRP prestressed concrete beams within the range of practical temperatures. This model is compared with a finite element mode (FEM) of a simply supported concrete beam prestressed with CFRP subjected to practical elevated temperatures. In addition, comparison is also made with an indirect reference to the real behavior of the material. The results of the model correlated reasonably with the finite element model and the real behavior. Finally, a practical application is provided.

Reconfiguration of NPC Multilevel Inverters to Mitigate Short Circuit Faults Using Back-to-Back Switches

The main focus of this paper is to propose a reconfiguration method to mitigate short circuit faults in a neutral point clamped multilevel inverter which is widely used as a power conversion system with distributed energy resources. Existing reconfiguration methods use either a redundant strategy or need a large number of additional devices pre-installed in the circuit; these will increase the bulk and complexity of the system. Most existing control-strategy-based methods distort the phase-toneutral voltage, which results in degradation of power quality. To maintain control-strategy-based reconfiguration, avoid significant change to the circuit topology, and avoid phase voltage distortion, a new and practical reconfiguration method is proposed in this paper. The proposed method is applicable to neural point clamped (NPC) multilevel inverters at any voltage level and can mitigate short circuit faults in any device. A technique of switching series connected switches is selected to combine with the proposed reconfiguration method since it's a practical design consideration for realistic implementation. MATLAB/Simulink is used to simulate a five-level NPC inverter with non-idealities to verify the proposed reconfiguration method. A five-level NPC is also built and tested to experimentally verify the proposed method. Short circuit faults are injected to different devices and the proposed method is verified to quickly and effectively recover the NPC inverter from these faulty conditions.

Topology and shape optimization with explicit geometric constraints using a spline-based representation and a fixed grid

Topology optimization is a computational method for finding the distribution of material such that an objective function is minimized subject to a set of constraints. In the context of structures, topology optimization aims to find the layout by changing the shape of the boundary and the number and shape of holes. Such optimized designs ultimately lead to energy savings, efficient usage of materials, and to faster and sustainable manufacturing. In this paper, we present an optimization approach that is based on explicit B-spline representation of the design, conforming with CAD standards. This parametrization enables to incorporate explicit constraints on minimum and maximum areas of holes and on curvatures of boundaries. Therefore practical design considerations such as avoiding stress concentrations in sharp corners and flexibility with respect to locations and sizes of holes can be embedded into the optimization problem. Furthermore, control of curvature can simplify machining processes leading to more efficient and sustainable manufacturing.

Millimeter-Wave 5G Antennas for Smartphones: Overview and Experimental Demonstration

For the first time to the best of our knowledge, this paper provides an overview of millimeter-wave (mmWave) 5G antennas for cellular handsets. Practical design considerations and solutions related to the integration of mmWave phased-array antennas with beam switching capabilities are investigated in detail. To experimentally examine the proposed methodologies, two types of mesh-grid phased-array antennas featuring reconfigurable horizontal and vertical polarizations are designed, fabricated, and measured at the 60 GHz spectrum. Afterward the antennas are integrated with the rest of the 60 GHz RF and digital architecture to create integrated mmWave antenna modules and implemented within fully operating cellular handsets under plausible user scenarios. The effectiveness, current limitations, and required future research areas regarding the presented mmWave 5G antenna design technologies are studied using mmWave 5G system benchmarks.

Functional disability and other health-related quality-of-life domains: points to consider for clinical trials in systemic sclerosis.

Patients with SSc have the highest mortality among the rheumatic diseases. In addition, SSc is associated with disfigurement, hand contractures, fatigue, poor sleep, severe RP with numbness and tingling of the fingers can lead to decrements in quality of life. This Points to Consider article provides practical considerations for design of trials for functional disability and other health-related quality-of-life issues.

Turning theory to practice in model-based FDI: Successful application to new generation Airbus aircraft

This paper presents a parametric model-based monitoring technique for detection and confirmation of faults in control surface servo-loops related to the Electrical Flight Control System. It is shown that there exists a direction in the parameter space which is sensitive to the occurrence of the faults on interest. On-line system parameter estimation is combined with an appropriate parametric test decision for robust detection and confirmation of faults. The paper reports on a number of identified practical design considerations that should go along with the basic design in order to provide a viable technological solution. The method presented in this paper has reached level 5 on Technological Readiness Level scale under Validation & Verification investigations at Airbus, and is considered to be a credible unconventional option to support (not rule out) conventional industrial practices.

Hybrid, Multi-Megawatt HVDC Transformer Topology Comparison for Future Offshore Wind Farms

With the wind industry moving further offshore, High Voltage Direct Current (HVDC) transmission is becoming increasingly popular. HVDC transformer substations are not optimized for the offshore industry though, increasing costs and reducing redundancy. A suggested medium frequency, modular hybrid HVDC transformer located within each wind turbine nacelle could mitigate these problems, but the overall design must be considered carefully to minimize losses. This paper’s contribution is a detailed analysis of the hybrid transformer, using practical design considerations including component library minimization. The configurations investigated include combinations of single phase H-Bridge and Modular Multilevel Converter topologies operating under minimum switching frequency control strategies. These were modelled in the MATLAB/Simulink environment. The impact of the minimum switching control strategy and converter topology on power transfer stability and overall efficiency is then investigated. It was found that the H-Bridge converter generated the lowest overall losses, but there was a trade off with power flow sensitivity due in part to the additional harmonics generated.

Practical Design Considerations for Lightweight Windshield Applications

Practical Design Considerations for Lightweight Windshield Applications

Design of an OFDM Physical Layer Encryption Scheme

This paper presents a new encryption scheme implemented at the physical layer of wireless networks employing orthogonal frequency-division multiplexing (OFDM). The new scheme obfuscates the subcarriers by randomly reserving several subcarriers for dummy data and resequences the training symbol by a new secure sequence. Subcarrier obfuscation renders the OFDM transmission more secure and random, whereas training symbol resequencing protects the entire physical layer packet but does not affect the normal functions of synchronization and channel estimation of legitimate users while preventing eavesdroppers from performing these functions. The security analysis shows that the system is robust to various attacks by analyzing the search space using an exhaustive key search. Our scheme is shown to perform better in terms of search space, key rate, and complexity in comparison with other OFDM physical layer encryption schemes. The scheme offers options for users to customize the security level and the key rate according to the hardware resource. Its low complexity nature also makes the scheme suitable for resource-limited devices. Details of practical design considerations are highlighted by applying the approach to an IEEE 802.11 OFDM system case study.

이륜 역진자 로봇의 제어 시스템 개발을 위한 설계 고려사항

This paper addresses some practical design considerations to build a two-wheeled inverted pendulum (TWIP) robot control system. The first issue is to identify the relationship between the primary parameters of the TWIP robot and the guaranteed stability of the time-delayed control loop. Secondly, the required data update rate and the required sensor/actuator performance are suggested for implementing a real-time digital control system. The final issue is concerned with improving the driving performance by investigating the reliability of the inertial sensor for attitude control and the backlash problem in the transmission mechanism.

A PSFB-Based Integrated PEV Onboard Charger With Extended ZVS Range and Zero Duty Cycle Loss

A conventional phase-shift full-bridge (PSFB) converter suffers from easy failure of zero-voltage switching (ZVS) in the lagging leg under light load conditions. This poses a significant challenge to the optimal design of PSFB-based plug-in electric vehicle (PEV) onboard chargers. In this paper, a self-reconfigured integrated onboard charger architecture is proposed for PEVs to cope with this design challenge. In this architecture, the PSFB converter is adopted as the main topology to charge the high-voltage battery pack, while the half-bridge LLC resonant converter is employed to charge the low-voltage auxiliary battery. Under light-charging mode, the half-bridge LLC converter is reconfigured to be paralleled with the PSFB topology to guarantee the ZVS of the lagging leg mosfet s. Moreover, a capacitor–diode–diode snubber is added to resolve the duty cycle loss issue of the PSFB converter and to reduce the circulating current. Practical design considerations are presented for both the PSFB and the half-bridge LLC converters. Frequency modulation and the phase-shift modulation provide two degrees of freedom to regulate the output voltage/current of both converters. The proposed charger architecture maintains low cost and high efficiency in this specific application. A 390 V input, 420 V/2.4 A, 14 V/21 A outputs, 1.3 kW rated converter prototype is designed, analyzed, and tested to verify the proof of concept.

Practical Immuno-PET Radiotracer Design Considerations for Human Immune Checkpoint Imaging.

Immune checkpoint blockade has emerged as a promising cancer treatment paradigm. Unfortunately, there are still a large number of patients and malignancies that do not respond to therapy. A major barrier to validating biomarkers for the prediction and monitoring of responders to clinical checkpoint blockade has been the lack of imaging tools to accurately assess dynamic immune checkpoint expression. Here, we sought to optimize noninvasive immuno-PET imaging of human programmed death-ligand 1 (PD-L1) expression, in a preclinical model, using a small high-affinity engineered protein scaffold (HAC-PD1). Six HAC-PD1 radiotracer variants were developed and used in preclinical imaging and biodistribution studies to assess their ability to detect human PD-L1 expression in vivo. Radiotracer design modifications included chelate, glycosylation, and radiometal. HACA-PD1 was adopted as the naming convention for aglycosylated tracer variants. NOD scid γ-(NSG) mice were inoculated with subcutaneous tumors engineered to either be constitutively positive (CT26 hPD-L1) or be negative (ΔmPD-L1 CT26) for human PD-L1 expression. When the tumors had grown to an average size of 1 cm in diameter, mice were injected with 0.75-2.25 MBq (∼10 μg) of an engineered radiotracer variant and imaged. At 1 h after injection, organs were harvested for biodistribution. Of the practical immuno-PET tracer modifications considered, glycosylation was the most prominent design factor affecting tracer uptake, specificity, and clearance. In imaging studies, aglycosylated 64Cu-NOTA-HACA-PD1 most accurately visualized human PD-L1 expression in vivo. We reasoned that because of the scaffold's small size (14 kDa), its pharmacokinetics may be suitable for labeling with the short-lived and widely clinically available radiometal 68Ga. At 1 h after injection, 68Ga-NOTA-HACA-PD1 and 68Ga-DOTA-HACA-PD1 exhibited promising target-to-background ratios in ex vivo biodistribution studies (12.3 and 15.2 tumor-to-muscle ratios, respectively). Notably, all HAC-PD1 radiotracer variants enabled much earlier detection of human PD-L1 expression (1 h after injection) than previously reported radiolabeled antibodies (>24 h after injection). This work provides a template for assessing immuno-PET tracer design parameters and supports the translation of small engineered protein radiotracers for imaging human immune checkpoints.

The Collaborative Cross Resource for Systems Genetics Research of Infectious Diseases.

An increasing body of evidence highlights the role of host genetic variation in driving susceptibility to severe disease following pathogen infection. In order to fully appreciate the importance of host genetics on infection susceptibility and resulting disease, genetically variable experimental model systems should be employed. These systems allow for the identification, characterization, and mechanistic dissection of genetic variants that cause differential disease responses. Herein we discuss application of the Collaborative Cross (CC) panel of recombinant inbred strains to study viral pathogenesis, focusing on practical considerations for experimental design, assessment and analysis of disease responses within the CC, as well as some of the resources developed for the CC. Although the focus of this chapter is on viral pathogenesis, many of the methods presented within are applicable to studies of other pathogens, as well as to case–control designs in genetically diverse populations.

Construction and testing of self-drilled soil nails

Current standards and best practice guidance recognise that testing of self-drilled hollow bar soil nails can be problematic as conventional packers and debonded lengths cannot be constructed. As a result, this causes difficulty in testing and confirming the ultimate bond resistance within the passive zone of a soil-nailed slope, and thus the design soil nail lengths. This paper provides a summary and review of the various testing procedures adopted for a soil nail construction project in Scotland. The practical design considerations, and their validation through the installation and testing of 49 sacrificial test nails, are detailed. The construction issues associated with the nail installation and testing are also outlined and discussed in light of the results obtained using different testing approaches. The aim of this case study is to report on the experiences with installation and testing of hollow bar soil nails. The objectives are to develop an initial data base of available soil–grout bond strength of hollow bar soil nails based on the several practical installation procedures used in this project and to establish areas for improvement of installation, testing and quality control in order to perform comparable pullout tests on self-drilled hollow bar soil nails.

Some practical considerations in three-arm non-inferiority trial design.

Non-inferiority trials aim to demonstrate whether an experimental therapy is not unacceptably worse than an active reference therapy already in use. When applicable, a three-arm non-inferiority trial, including an experiment therapy, an active reference therapy, and a placebo, is often recommended to assess assay sensitivity and internal validity of a trial. In this paper, we share some practical considerations based on our experience from a phase III three-arm non-inferiority trial. First, we discuss the determination of the total sample size and its optimal allocation based on the overall power of the non-inferiority testing procedure and provide ready-to-use R code for implementation. Second, we consider the non-inferiority goal of 'capturing all possibilities' and show that it naturally corresponds to a simple two-step testing procedure. Finally, using this two-step non-inferiority testing procedure as an example, we compare extensively commonly used frequentist p -value methods with the Bayesian posterior probability approach. Copyright © 2016 John Wiley & Sons, Ltd.