Special Design Techniques Research Articles

Flying a Quadcopter—An Audio Entertainment and Training Game for the Visually Impaired

With the increase in the number of sensory substitution devices, the engineering community is confronted with a new challenge: ensuring user training in safe virtual environments before using these devices in real-life situations. We developed a game that uses an original sonification model, which, although not specific to a certain substitution device, can be an effective means of training for orientation in space based on audio stimuli. Thus, the game is not only a means of entertainment for visually impaired (VI) people but also one of training for the use of assistive devices. The game design and audio design are original contributions by the authors. The sonification model, which is crucial for a game dedicated to visually impaired people, is described in detail, both at the user and the implementation level. For better immersion, special sound design techniques have been used, such as ambisonic recordings and impulse response (IR) recordings. The game has been improved gradually, especially the sonification model, based on users’ feedback.

Air-Ground Integrated Sensing and Communications: Opportunities and Challenges

The air-ground integrated sensing and communications (AG-ISAC) network, which consists of unmanned aerial vehicles (UAVs) and ground terrestrial networks, offers unique capabilities and demands special design techniques. In this article, we provide a review on AG-ISAC, by introducing UAVs as "relay" nodes for both communications and sensing to resolve the power and computation constraints on UAVs. We first introduce an AG-ISAC framework, including the system architecture and protocol. Four potential use cases are then discussed, with the analysis on the characteristics and merits of AG-ISAC networks. The research on several critical techniques for AG-ISAC is then discussed. Finally, we present our vision of the challenges and future research directions for AG-ISAC, to facilitate the advancement of the technology.

Analysis of Single Event Transient Effects in Standard Delay Cells Based on Decoupling Capacitors

Single Event Transients (SETs), i.e., voltage glitches induced in combinational logic as a result of the passage of energetic particles, represent an increasingly critical reliability threat for modern complementary metal oxide semiconductor (CMOS) integrated circuits (ICs) employed in space missions. In rad-hard ICs implemented with standard digital cells, special design techniques should be applied to reduce the Soft Error Rate (SER) due to SETs. To this end, it is essential to consider the SET robustness of individual standard cells. Among the wide range of logic cells available in standard cell libraries, the standard delay cells (SDCs) implemented with the skew-sized inverters are exceptionally vulnerable to SETs. Namely, the SET pulses induced in these cells may be hundreds of picoseconds longer than those in other standard cells. In this work, an alternative design of a SDC based on two inverters and two decoupling capacitors is introduced. Electrical simulations have shown that the propagation delay and SET robustness of the proposed delay cell are strongly influenced by the transistor sizes and supply voltage, while the impact of temperature is moderate. The proposed design is more tolerant to SETs than the SDCs with skew-sized inverters, and occupies less area compared to the hardening configurations based on partial and complete duplication. Due to the low transistor count (only six transistors), the proposed delay cell could also be used as a SET filter.

ColdADC_P2: A 16-Channel Cryogenic ADC ASIC for the Deep Underground Neutrino Experiment

The second and final version of ColdADC, called ColdADC&#x005F;P2, is presented. ColdADC&#x005F;P2 is a 16-channel, 12-bit, 2 MS/s digitizer application-specific integrated circuit (ASIC) intended for use inside the DUNE Far Detector. ColdADC&#x005F;P2 contains two 16 MS/s pipelined analog-to-digital converters (ADCs) that each digitizes the output of eight sample-and-hold amplifiers (SHAs). Because the application requires immersion in liquid argon (LAr), ColdADC&#x005F;P2 was developed using specialized design techniques for long-term reliability in cryogenic environments and a customized cryogenic standard cell library. ColdADC&#x005F;P2, with a die area of approximately 52.4 mm² and fabricated in 65-nm CMOS technology, achieves 130-<inline-formula> <tex-math notation="LaTeX">$\mu \text{V}$ </tex-math></inline-formula> rms noise performance and 11.8-bit effective-number-of-bits (ENOB) at a temperature of 77 K, with channel-to-channel crosstalk of &#x003C; 0.06&#x0025; while dissipating 338 mW (21 mW per channel). Residual nonlinearity that is consistent with dielectric absorption in the capacitors internal to the ADC is corrected using a lookup table.

One Line Soft Keyboard with T9-keys Layout Proposal on Smartwatch Touch Screen Device

A smartwatch is a mini-sized digital computer device that functions apart from being a watch and can also perform intelligent computing tasks. Due to screen size limitations, a smartwatch requires special design techniques on its input and output to allow interaction with its users. Text entry is often required by many applications, but because the smartwatch screen is small, text entry techniques commonly used on personal computers are impractical when applied to smartwatches. In this study, we introduce a design concept proposal for a soft keyboard called One Line Soft Keyboard with T9-Keys Layout. The soft keyboard design concept is expected to reduce the space on the keyboard on the smartwatch screen, along with the use of widely used button layouts that are familiar to users.

Development of a Wearable Remote Cardiac Health Monitoring with Alerting System

Remote monitoring with alerting systems becomes unavoidable in the field of remote healthcare. The efficiency of such a system depends on accuracy, easy-to-use, versatility, and cost-effectiveness. In this study, a remote cardiac health monitoring along with the alert raising facility is presented. Special design techniques have been adopted to craft the photoplethysmography (PPG) sensor to overcome the congenital limitations like pressure disturbance, the influence of ambient light and motion artifacts. Three key components like pulse rate (PR), blood pressure (BP) and heart rate variability (HRV) are considered to monitor the cardiac health status. A novel algorithm has been developed to detect the cardiac health status of any subject from the above-mentioned physiological parameters. Also, the variation of human skin tone across demography is considered to minimize the impact of skin structure variability in PPG-based cardiac parameter measurement. Decentralized remote monitoring architecture is implemented using the virtual network computing (VNC) platform. We conducted a trial where the training dataset consisted of data from 70 volunteers and the trial dataset considered 20 new volunteers. The overall accuracy of cardiac health monitoring achieved is 98.5%. The experimental results demonstrate the good promise of reliable and efficient system architecture.

Feasibility and performance of ground source heat pump systems for commercial applications in tropical and subtropical climates

The feasibility of installation and performance of vertical ground source heat pump (GSHP) systems for heating and cooling of a typical 9000 m2 office building located in ten metropolitan cities with tropical and subtropical climates are investigated. The heating and cooling loads of the identical building in the ten cities are simulated using the EnergyPlus software. For each location, the design of the GSHP system is performed using the ground loop design (GLD) software, and the performance of the GSHP system is assessed. A multi-year cost analysis is also carried out to assess the feasibility of installation of GSHP systems from an economic point of view. It is found that GSHP systems may not be economically viable for the cities in tropical climates, particularly those near the equator, because of inefficient performance and high cooling demand. Thermal imbalance in soil caused by significantly greater cooling demand than heating demand may further exacerbate the system in tropical cities. However, the implementation of GSHP may turn into a feasible option for some of the tropical cities located near the Tropic of Cancer by adopting special design techniques or including additional hybrid energy sources. GSHP systems seem to be economically feasible and operationally efficient in the cities with subtropical climates where more balance between heating and cooling loads exist.

Embedded real-time systems in cyber-physical applications: a frequency domain analysis methodology

ABSTRACTCyber-Physical Systems (CPSs) use sensors and actuators to interface between an embedded system and the physical world. The time-continuous domain of the physical world should be periodically sampled by real-time tasks in an embedded system to preserve its dynamic properties in the time-discrete domain.Because the task execution pattern may vary during runtime, a jitter in the execution of a real-time task hinders the periodicity of its execution. The effects of jitters in CPSs are difficult to determine when the premises of the Nyquist-Shannon sampling theorem are not satisfied.This paper proposes using frequency domain analysis to determine the perturbations that a real-time system produces on real-world applications; accordingly, the paper defines both a design and an evaluation criterion for real-time systems in CPS applications. The Fixed Priority discipline is analysed through simulations to conclude that no special design techniques are required when the utilization factors are less than 20%.

Frequency Interleaving IF Transmitter and Receiver for 240-GHz Communication in SiGe:C BiCMOS

This article presents a fully integrated modular wideband frequency interleaving (FI) transmitter and receiver for high data rate communication applications. At the transmitter side, three independent in-phase and quadrature-phase (IQ) baseband channels are upconverted to different intermediate frequencies (IFs) and then interleaved. At the receiver side, the interleaved signals are downconverted and separated back to each independent channel. Single-ended inputs and outputs are utilized to reduce the pin count, for a more practical realization and higher potential toward future system scaling. Special design techniques are followed to minimize crosstalk and intermodulation products between the channels. All circuits are manufactured and measured in a 130-nm SiGe:C BiCMOS technology with $f_{\textbf {T}}/f_{\textbf {max}}$ =300/500 GHz. The FI transmitter achieves a channel bandwidth of 2.5 GHz with less than 3-dB difference across different channels until 15-GHz IF. It consumes 560 mW from 2.5 and 3.3 V supplies and occupies a silicon area of 1.9 mm2. The FI receiver achieves a baseband channel bandwidth of 2.5 GHz with a 1-dB difference between the channels until the same IF. It consumes 860 mW from 2.5 and 3.3 V supplies and has a chip area of 1.55 mm2. The circuits are deployed in a communication experiment; first, in a back-to-back test with a direct cable connection, demonstrating a data rate of 15.6 Gb/s across the three IQ channels with a 16-QAM modulation scheme and a worst case transmitter-to-receiver error vector magnitude (EVM) of −18.6 dB. Then, a wireless experiment is performed with a 240-GHz front end with on-chip antenna, demonstrating a data rate of 7.8 Gb/s with QPSK modulation and a worst case EVM of −8.3 dB, across a wireless link of 15 cm. To the best of our knowledge, this is the first article that demonstrates a wireless transmission at sub-terahertz (sub-THz) carrier frequencies utilizing FI architectures.

Technical and economic evaluation of separation of dimethyl disulfide from disulfide oil at liquefied petroleum gas treatment facilities of Assaluyeh gas refinery

AbstractDisulfide oil (DSO) is produced as a hydrocarbon sulfide waste stream in liquefied petroleum gas and condensate sweetening units in refineries and can cause acute environmental pollutions. In this article, a simple process composed of two units including a distillation unit and a hydrodesulfurization (HDS) unit is proposed to overcome the disulfide oil problem in refineries. The commercial HDS catalyst is CoMo type that is applicable for hydrotreating of DSO. This catalyst is developed by different licensors such as Axens. The high sulfur content in DSO feed causes an increase in heat of reaction and partial pressure of H2S in HDS reactor. By using special design techniques such as reactor quenching or increase H2/oil ratio, the reactor can be designed properly for DSO feed. The waste stream DSO is converted to valuable products including: dimethyl disulfide (DMDS), sweet gas and condensate. A process flow diagram consisting of distillation and HDS units together with amine treating and hydrogen compression system is proposed and simulation of the process is carried out by Aspen plus: The distillation unit separates DMDS and the HDS unit removes sulfur from remainder DSO. Capital cost estimation methodology is based on bare module factor. The capital and operating cost of the process are estimated for a real capacity of DSO just produced in south pars of Iran. Financial parameters and sensitivity analysis show that the process is feasible both technically and economically with an internal rate of return of 73.6%. The proposed process is accepted environmentally by converting a harmful waste to saleable products.

A Novel Modular Radiation Hardening Approach Applied to a Synchronous Buck Converter

Radiation and extreme temperature are the main inhibitors for the use of electronic devices in space applications. Radiation challenges the normal and stable operation of DC-DC converters, used as power supply for onboard systems in satellites and spacecrafts. In this situation, special design techniques known as radiation hardening or radiation tolerant designs have to be employed. In this work, a module level design approach for radiation hardening is addressed. A module in this sense is a constituent of a digital controller, which includes an analog to digital converter (ADC), a digital proportional-integral-derivative (PID) controller, and a digital pulse width modulator (DPWM). As a new Radiation Hardening by Design technique (RHBD), a four module redundancy technique is proposed and applied to the digital voltage mode controller driving a synchronous buck converter, which has been implemented as hardware-in-the-loop (HIL) simulation block in MATLAB/Simulink using Xilinx system generator based on the Zynq-7000 development board (ZYBO). The technique is compared, for reliability and hardware resources requirement, with triple modular redundancy (TMR), five modular redundancy (FMR) and the modified triplex–duplex architecture. Furthermore, radiation induced failures are emulated by switching all duplicated modules inputs to different signals, or to ground during simulation. The simulation results show that the proposed technique has 25% and 30%longer expected life compared to TMR and FMR techniques, respectively, and has the lowest hardware resource requirement compared to FMR and the modified triplex–duplex techniques.

Method of winch drive permanent magnet inverted motor design

Designing a permanent magnet synchronous motor (PMSM) of a winch drive needs to take into account the features of this machine. The engine has an inverted design with limited dimensions, is powered by a fre-quency converter, runs at the nominal power frequency and nominal load without using the damping winding and frequency start, and provides the required range of rope winding speeds. There is no specialized engi-neering design methodology for the winch drive PMSM. It is required to make changes and additions to the existing methods of designing synchronous machines when solving the problem of designing a winch drive PMSM. Design and validation calculations were performed in the Mathcad environment based on the tech-nique of designing machines with V.A. Balagurov’s permanent magnets and methods of designing general-purpose industrial synchronous machines with electromagnetic excitation. Field models of PMSM were used for modelling electromechanical processes and thermal status. The developed technique of designing the winch drive permanent magnet inverted motor is different from the known methods and due to this allows accounting for the design features of PMSM in the calculation of the size of the machine, the magnets, the stator core, the choice of electromagnetic loads, the design of the stator winding, the choice of the cooling system and the steel grade of the stator core. The specific requirements of the technical specification are taken into account when calculating the number of poles and the frequency of the supply voltage. A design project of the inverted PMSM of the winch drive has been developed. And the paper presents the design and verification calculations results. The reliability of the results was checked by field modeling of electromechanical processes and the thermal state of the PMSM. The study has solved the problem of no specialized engineering design techniques of the winch drive PMSM. The technique can be used by electromechanical engineers in solving the problem of designing winch drive PMSM as it allows making a design project of the PMSM corresponding to the requirements of the technical specifications and operation feature.

Self-cleaning spacesuits for future planetary missions using carbon nanotube technology

Lunar dust proved to be troublesome during the Apollo missions. The powdery dust got into everything, abrading spacesuit fabric, clogging seals and other critical equipment. Even inside the lunar module, Apollo astronauts were exposed to this dust after they removed their dust coated spacesuits. The lunar dust is comprised of fine particles, with electric charges imparted by solar winds and ultraviolet radiation. As such, it adheres readily, and easily penetrates through the smallest crevices into mechanisms. While efforts are under way to figure out how to return astronauts to the Moon and set up habitats for long duration missions, the issue of lunar dust remains relevant. Consequently, NASA has identified dust as a critical environmental challenge to overcome for future planetary surface missions characterized by dusty environments.Several concepts were successfully investigated by the international research community for preventing deposition of lunar dust on rigid surfaces (ex: solar cells and thermal radiators). However, applying these technologies for flexible surfaces and specifically to spacesuits has remained an open challenge, due to the complexity of the suit design, geometry, and dynamics. In our research, we developed a SPacesuit Integrated Carbon nanotube Dust Ejection/Removal (SPIcDER) system to protect spacesuits and other flexible surfaces from lunar dust. SPIcDER leverages the efficient Electrodynamic Dust Shield concept developed at NASA for use on solar cells. It is customized for dust mitigation on flexible surfaces, using novel materials and specialized design techniques. The result is a self-cleaning spacesuit that can repel lunar dust.This paper provides an overview of the SPIcDER system and showcases our working prototypes, ranging from coupons to a scaled portion of a lunar spacesuit segment. The design is supported by parametric analysis in ANSYS Maxwell for optimizing SPIcDER integration into the spacesuit outerlayer. The paper emphasizes design considerations for astronaut safety, based on analysis and experimental results. The SPIcDER system can be optimized efficiently for potential missions to Mars and asteroids, as well as for Earth based applications.

Considering nonlinear properties of concrete in the design of reinforced concrete structures for torsion

Restoration and maintenance of cultural heritage concrete and reinforced objects always require accounting for the torsional stress in the elements, as well as the tensile, compressive and shearing stress. It should be considered, that torsion always develops in the elements of spatial structures, including cross-ribbed systems, bridges and overlaps, elements of shells and domes, stairs, etc. This paper briefly systematizes substantive results of the last studies of an urgent problem of torsional stiffness of reinforced concrete elements, including theoretical investigations, experimental studies and numerical research. Stress redistribution in the statically indeterminate reinforced concrete structures’ elements depends on both torsional and bending stiffness. However, while bending stiffness is considered in the design practice, the torsional stiffness is not aknowledged by engineers, nor used in building standards and software packages. This paper aims to substantiate the necessity of considering the torsional stiffness of reinforced concrete elements in design practice. This article is the result of numerous investigations conducted in the scientific school of professor Taliat Azizov. They certify that reduction of the torsional stiffness must be considered along with the bending stiffness in different stages of behaviour of concrete structures. Moreover, the research conducted for this paper proved that a change in the shear modulus of concrete also affects the deflected mode of structures and should be accounted for as the component of torsional stiffness. In order to provide engineers with specialized design techniques, they have been developed for the calculation of torsional stiffness of reinforced concrete elements with normal cracks of rectangular, triangular, t-sections, box-sections, and other cross-sections. The engineering bilinear shear stress-strain curve for concrete has also been proposed on the basis of experimental studies.

Исследование интегральных характеристик охлаждающей системы с термоэлектрическим модулем

Thermoelectric modules (TEM) are devices using which it is possible to implement either thermoelectric cooling due to the Peltier effect or electricity generation due to the Seebeck effect. In the first case, electric energy is directly converted into thermal energy, and in the second case, thermal energy is converted into electricity. Recent advances in the development of new thermoelectric nanostructured materials with characteristics significantly better than those found in bulk ones, prompted an increased interest in cooling and electricity generation through the use of thermoelectric devices. Special engineering design techniques are used in developing thermoelectric systems. However, such techniques only yield successful results for some simple designs. If the design of a thermoelectric device is non-trivial, some approximations have to be applied for the design, which seriously affects the accuracy of the result. The existing engineering methods for calculating the parameters and integral characteristics of TEMs involve a large number of simplifications and shortcomings, due to which the calculated integral characteristics of a TEM can differ significantly from their actual ones. In the field of thermoelectric devices, numerical simulation has to be used to solve various problems, in particular, for studying and evaluating promising designs of thermoelectric devices. The article presents the mathematical model of a cooling system equipped with TEMs. Numerical solution of the conjugate heat transfer equations describing the cooling system operation is obtained. It is shown that the TEM operating parameters are influenced by a number of factors that should preferably be taken into account in temperature distribution calculations. It is also shown that under real conditions the integral TEM operation parameters may differ considerably from those calculated according to the standard engineering procedures. Owing to its containing a rigorous body of mathematics, the developed model makes it possible to calculate the TEM parameters and integral characteristics under the real conditions of their operation.

Design techniques for a stable operation of cryogenic field-programmable gate arrays.

In this paper, we show how a deep-submicron field-programmable gate array (FPGA) can be operated more stably at extremely low temperatures through special firmware design techniques. Stability at low temperatures is limited through long power supply wires and reduced performance of various printed circuit board components commonly employed at room temperature. Extensive characterization of these components shows that the majority of decoupling capacitor types and voltage regulators are not well behaved at cryogenic temperatures, asking for an ad hoc solution to stabilize the FPGA supply voltage, especially for sensitive applications. Therefore, we have designed a firmware that enforces a constant power consumption, so as to stabilize the supply voltage in the interior of the FPGA. The FPGA is powered with a supply at several meters distance, causing significant resistive voltage drop and thus fluctuations on the local supply voltage. To achieve the stabilization, the variation in digital logic speed, which directly corresponds to changes in supply voltage, is constantly measured and corrected for through a tunable oscillator farm, implemented on the FPGA. The impact of the stabilization technique is demonstrated together with a reconfigurable analog-to-digital converter (ADC), completely implemented in the FPGA fabric and operating at 15 K. The ADC performance can be improved by at most 1.5 bits (effective number of bits) thanks to the more stable supply voltage. The method is versatile and robust, enabling seamless porting to other FPGA families and configurations.

A 32-Channel 13-b ADC for Space Applications

This paper presents a 13-b, 2.56-μs conversion time, 2 V input range, 32-channel single slope analog-to-digital converter (ADC) called OWB-1 and implemented in a 0.35-μm CMOS commercial technology. It is based on an improved Wilkinson architecture. An interpolator composed by a delay lock loop is used to increase the time resolution of the counter by a factor of 32, while keeping a low power consumption and ensuring the high dynamic performance of the ADC. Measurements performed on the ADC have shown that the noise is better than 0.86 LSB over the full conversion range, its differential nonlinearity is in the range of -0.28/+0.31 LSB and its integral nonlinearity is within -1.3/+2.1 LSB. The total power consumption of the chip is 57 mW for 32 active channels. A new temperature compensation system based on a servo loop has also been integrated into the chip to compensate for temperature effects in the -40°C to +40°C range. Special design techniques have been used to make the ASIC immune to single event latchup. OWB-1 readout is optimized for a new low power microgamma camera (Caliste-MC2) with digital output based on a 32 x 32 CdTe or CdZnTe pixel matrix.

A Review on Piezoelectric Energy Harvesting: Materials, Methods, and Circuits

Abstract Piezoelectric microelectromechanical systems (PiezoMEMS) are attractive for developing next generation self-powered microsystems. PiezoMEMS promises to eliminate the costly assembly for microsensors/microsystems and provide various mechanisms for recharging the batteries, thereby, moving us closer towards batteryless wireless sensors systems and networks. In order to achieve practical implementation of this technology, a fully assembled energy harvester on the order of a quarter size dollar coin (diameter=24.26 mm, thickness=1.75 mm) should be able to generate about 100 μW continuous power from low frequency ambient vibrations (below 100 Hz). This paper reviews the state-of-the-art in microscale piezoelectric energy harvesting, summarizing key metrics such as power density and bandwidth of reported structures at low frequency input. This paper also describes the recent advancements in piezoelectric materials and resonator structures. Epitaxial growth and grain texturing of piezoelectric materials is being developed to achieve much higher energy conversion efficiency. For embedded medical systems, lead-free piezoelectric thin films are being developed and MEMS processes for these new classes of materials are being investigated. Non-linear resonating beams for wide bandwidth resonance are also reviewed as they would enable wide bandwidth and low frequency operation of energy harvesters. Particle/granule spray deposition techniques such as aerosol-deposition (AD) and granule spray in vacuum (GSV) are being matured to realize the meso-scale structures in a rapid manner. Another important element of an energy harvester is a power management circuit, which should maximize the net energy harvested. Towards this objective, it is essential for the power management circuit of a small-scale energy harvester to dissipate minimal power, and thus it requires special circuit design techniques and a simple maximum power point tracking scheme. Overall, the progress made by the research and industrial community has brought the energy harvesting technology closer to the practical applications in near future.

A circularly polarized square microstrip parasitic antenna with an improved bandwidth

ABSTRACTThis paper presents a novel design for an optimized circularly polarized microstrip antenna. Circular polarized microstrip antennas have many uses due to its low profile design. However, one of the microstrip antenna's main limitations arises from its narrow frequency bandwidth. Therefore, it is necessary to use special design techniques in order to increase the operating frequency bandwidth while maintaining all of the other respectable optimum radiation characteristics. The proposed design involves using a dual‐feed square patch, which is gap coupled with two parasitic patches in a mirrored L‐shaped configuration. This design resulted in an axial ratio bandwidth of 11%, S11 bandwidth of 14% and a gain of 9 dB at the 2.15 GHz center frequency. The proposed design was built, and the measured results were in agreement with the simulation results. Additionally, this antenna design was used in an array structure in order to increase the gain, while maintaining a good axial ratio. These enhanced radiation results allow the use of the proposed antenna design in many domains such as wireless and military applications without facing the limitations of the narrow frequency bandwidth. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:597–603, 2016

Analysis and Characterization of Variability in Subthreshold Source-Coupled Logic Circuits

This article explores the effect of device parameter variations on the performance of subthreshold source-coupled logic (STSCL) circuits. A test chip has been fabricated in a standard CMOS 90 nm technology to study the matching properties of STSCL circuits. Both process variations and device mismatch have been included in this study. The performed analysis shows that while the STSCL topology is very robust against global variations mainly thanks to the adoption of an on-chip bias generator circuit, special design techniques are required to compensate for the effect of device mismatch. Proper device sizing as well as creating intentional mismatch in the biasing condition of STSCL gates are two effective approaches that have been investigated to overcome the variation related issues. Both die-to-die (D2D) and within-die (WID) variations in the delay of STSCL gates have been characterized and validated through measurements. A comprehensive analysis of timing jitter in STSCL-based ring oscillators is also presented.