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As the automotive industry has grown and lifestyle has changed, the time spent in an automobile has been gradually increasing. Accordingly, thermal comfort for passengers inside the cabin of an automobile is more important than before. Thermal comfort can be affected by several factors, such as temperature, humidity, and air distribution inside the cabin, as well as airflow rate and air velocity from the air vents and air-handling unit (AHU). The aim of this paper is to investigate the impact of changes in the pattern of discharge air from air vents connected with the vent duct and AHU on the thermal comfort in an automobile. The changed patterns of discharge air were of three types: diffuse-mode, focus-mode, and mix-mode. Cool-down performance and auto temperature-control performance experiments were performed to evaluate the thermal comfort of the front and rear passenger seats in the climate control wind tunnel. In addition, a road driving evaluation of the temperature difference between front and rear seats with two passengers was performed. As a result, focus- and diffuse-type air vents can be helpful for improving thermal comfort of passengers and the air stream of the cabin.

This brief presents a quarter-rate 1 finite impulse response and 1 infinite impulse response (IIR) direct decision feedback equalizer (DFE). The proposed non-time-overlapping data generation enables the elimination of all two-stacked clocked transistors in the 4:1 current-mode-logic multiplexer of conventional quarter-rate IIR DFEs. Therefore, the feedback delay is improved without static current in the multiplexer of this brief. Fabricated in a 65-nm CMOS, the DFE achieves a power efficiency of 0.43 pJ/b at a data rate of 10.8 Gb/s in 1-V supply. A BER < 10−12 for an eye width of 0.36 UI was verified over a 26-dB PCB channel loss. Core area is 0.00544 mm2.

This brief presents an input-data-jitter-tolerant injection-type clock and data recovery (CDR) circuit with a super-harmonic injection-locked ring oscillator (SH-ILRO). Unlike prior injection-type CDRs that utilize a power-hungry CML-type data injection path or for which the data rate is limited to the process-defined CMOS logic bandwidth, the proposed injection-type CDR achieves energy-efficient data edge injection. The proposed wide-bandwidth source follower-based edge detector extracts the input data edge energy efficiently. The proposed SH-ILRO enables quarter-rate injection-locking without high-speed injection selection logic. Fabricated in 65-nm CMOS, the prototype injection-type CDR consumes 19.08 mW at 12 Gb/s with 87-MHz jitter transfer bandwidth and more than 1.0 UIpp jitter tolerance at 20 MHz.

When a vehicle is parked under the summer sun, to avoid the passenger discomfort caused by high cabin temperature, the performance of forced ventilation, which is called pre-ventilation, using a solar sunroof integrated with a photovoltaic (PV) cell to reduce cabin thermal load is investigated numerically in this study. The vehicle pre-ventilation system is composed of a solar sunroof, DC/DC converter, and air handling system. The indoor thermal load is reduced by the hot cabin air that moves when outside air is supplied to the cabin. The simulation model is established with the component and system model approach using Dymola, and the numerical analysis results are compared with the experimental data. Using the validated model, pre-ventilation performance is analyzed with 40-, 80-, and 120-W PV cells in each solar sunroof system. The results indicate that the 40-W PV cell in the solar sunroof is sufficient for this pre-ventilation application considering cost and cabin thermal comfort performance. Further, the effects on cabin space and DC/DC converter efficiencies were investigated. The analysis results show that cabin volume slightly affected cabin temperature, whereas the efficiency of DC/ DC converter was not significantly affected by cabin temperature reduction.

In this brief, a 0.9-V 12-Gb/s quarter-rate two finite impulse response tap direct decision feedback equalizer (DFE) is presented. For a high-speed incorporated operation of both DFE summing and slicing, a common-mode-controlled charge-based latch (CMCCBL) is proposed. In a CMCCBL-based DFE, the common mode of the first tap feedback signal is changed to adjust the first tap feedback weight. Therefore, CMCCBL does not need the conventional first tap weighting transistors which increase the DFE feedback delay. The DFE core compensates for the FR4 printed circuit board channel loss of −22 dB at 6 GHz and consumes 4.16 mW achieving 0.347 pJ/bit for PRBS7 input. The active area of DFE is 0.0036 mm2 in a 65-nm CMOS process.

Massive efforts to build walking aid platforms for the disabled have been made in line with the needs of the aging society. One of the core technologies that make up these platforms is a realization of the skin-like electronic patch, which is capable of sensing electromyogram (EMG) and delivering feedback information to the soft, lightweight, and wearable exosuits, while maintaining high signal-to-noise ratio reliably in the long term. The main limitations of the conventional EMG sensing platforms include the need to apply foam tape or conductive gel on the surface of the device for adhesion and signal acquisition, and also the bulky size and weight of conventional measuring instruments for EMG, limiting practical use in daily life. Herein, we developed an epidermal EMG electrode integrated with a wireless measuring system. Such the stretchable platform was realized by transfer-printing of the as-prepared EMG electrodes on a SiO2 wafer to a polydimethylsiloxane (PDMS) elastomer substrate. The epidermal EMG patch has skin-like properties owing to its unique mechanical characteristics: i) location on a neutral mechanical plane that enables high flexibility, ii) wavy design that allows for high stretchability. We demonstrated wireless EMG monitoring using our skin-attachable and stretchable EMG patch sensor integrated with the miniaturized wireless system modules.

This brief presents a 0.65-V power noise tolerant source-synchronous injection-locked receiver with 13.4 dB channel loss compensation. To meet the 1UI timing constraint for the decision feedback equalizer in low supply, SR latches are removed in the feedback path and return to zero recovered data is used for equalization. Additionally, a power noise sensitivity of low supply is relieved by current and pMOS body bias control techniques of an oscillator. The test core fabricated in 65-nm CMOS process achieves 11.2 Gb/s with 0.303 pJ/bit FOM compensating 13.4 dB channel loss at 5.6 GHz.

This brief presents a reference-less baud-rate digital clock and data recovery (CDR) with a data decision feedback (DDF) with a direct feedback method (DFM). The DDF with DFM has been used for the equalization of the channel loss for the serial link with a decision feedback equalizer. However, we apply DDF with DFM to the baud-rate CDR to reduce the number of data samplers, which is dropped to 2/3 compared to conventional baud-rate CDR. As a result, the power consumption and mismatch problem of the data samplers can be reduced. The test chip fabricated in 65-nm CMOS technology operates at a 10-Gb/s data rate with 13.84-mW power consumption.

The goal of this research is to investigate the application of low-cost climate control seats (CCSs) using a Heating, Ventilation and Air-conditioning system (HVAC). CCSs are being vigorously developed because demands on passengers’ thermal comfort are increasing recently. Nevertheless, current CCSs–thermo-electric devices (TED) that have been applied for both heating and cooling systems, have been used in limited luxury cars only. HVAC-type CCSs are proper for effective delivery of conditioned air due to thermal comfort and close proximity to passengers. In this study, experimental results show that HVAC-type CCSs have superior cooling performance and slightly worse heating performance than that of TED-type CCSs. In the case of HVAC-type CCSs, compared to TED-type CCSs, airflow volume was increased approximately 3.7–7.3 m3/h and surface temperature of seats was reduced by about 5 °C. And the maximum cool-down performance of HVAC-type CCSs was similar to the Base (Non HVAC-type CCSs). In addition, in passengers’ subjective evaluation, the HVAC-type CCSs, the former recorded twelve minutes to reach the comfort rate five both in cooling and heating test, meanwhile, TED-type CCSs are nineteen minutes and ten minutes each both in the cooling and heating test.

The ISG (Idle Stop and Go) systems are commonly used in modern automobiles because they are economical and environmental friendly technology. However, when a vehicle stops, the air-conditioning system stops, resulting in thermal discomfort to passengers in the cabin. This paper examines a cold storage heat-exchanger (CSH) integrated with an evaporator. The position of the cold storage parts inside a heat exchanger was analyzed through numerical simulations using FLUENT to create an adequate design for a CSH. The CSH performance was then examined with various airflow volumes and optimized experimentally in terms of the refrigerant flow circuit and fin density in the heat exchanger. Next, an experiment on the coldness release performance of the CSH was conducted in the air-conditioning system. The cold storage system with optimized CSH experiment resulted in lower air discharge temperatures (3.5 °C ~ 4.9 °C) than current air-conditioning systems, and delayed the warm-up by approximately 155 seconds to reach 18 °C temperature of air discharge. For this study, the CSH is an effective solution for the ISG-applied vehicles with less investment by transforming current air-conditioners’ structures more effectively.

Deep neural networks (DNNs) are widely used for real-world applications. However, large amount of kernel and intermediate data incur a memory wall problem in resource-limited edge devices. The recent advances of a binary deep neural network (BNN) and a computing in-memory (CIM) have effectively alleviated this bottleneck especially when they are combined together. However, previous CIM-based accelerators for BNN are highly vulnerable to process/supply voltage/temperature (PVT) variation, resulting in severe accuracy degradation which makes them impractical to be employed in real-world edge devices. To address this vulnerability, we propose a PVT-robust accelerator architecture for BNN with a computable 4T embedded DRAM (eDRAM) cell array. First, we implement the XNOR operation of BNN in a time-multiplexed manner by utilizing the fundamental read operation of the conventional eDRAM cell. Next, a PVT-robust bit-count based on charge sharing is proposed with a computable 4T eDRAM cell array. In result, the proposed architecture achieves 6.9× less variation in PVT-variant environments which guarantees a stable accuracy and 2.03-49.4× improvement of energy efficiency over previous CIM-based accelerators.

Employing magnetic beads (MBs) to microfluidic chips has enabled diverse microscale biomedical applications involving isolation of target molecules, such as, separation, and biosensing. In this report a microfluidic immunoassay chip that can temporarily immobilize MBs for the detection of target biomarkers within a sample solution flown through its channels is introduced. A through-hole structure of the MB capture zone and valves that can control the direction of the flow enabled immobilization of MBs with high reproducibility. Controlling immobilization of MBs shows promise for reproducible immunoassay signal detections for the same concentration of biomarker which is crucial for quantification of the assay. In addition, the structure and position of the captured MBs can potentially be optimal for immunoassay performances where immunoassay reagents including the antigen and the detection antibody are flown through the MB captured through hole maximizing contact for high binding efficiencies.

The ISG (Idle Stop and Go) system isvery useful in the automobile industry because it increases fuel consumption and reduces green house gas emissions. However, when the engine is on standby, the air-conditioning system does not work due to compressor inactivity, causing thermal discomfort to passengers. This study examines the thermal storage system, which is a cold storage heat exchanger integrated with a current evaporator. The experiments were conducted for an optimum cold storage heat exchanger design with various fin heights and densities, a number of stacking evaporator plates, refrigerant flow circuits inside the evaporator, and PCMs (Phase Change Materials) in the heat exchanger. The effects of coldness-release performance were examined with various ambient temperatures and air flow volume rates to the cold storage heat exchanger. The visualization of PCM’s freezing and melting was conducted with the cold storage heat exchanger. From the results, we found that the air discharge temperature of the air-conditioning system that was applied to the optimum cold storage heat exchanger was delayed around 540 seconds compared to the current air-conditioning system to reach 24 °C. Thus we can say that the cold storage heat exchanger integrated with an evaporator is an effective solution for ISG vehicles in maintaining thermal comfort in vehicle cabins during short engine stops.

The aim of this paper is to investigate the possibility of using an R-134a heat pump system with a conventional air-conditioning system for zero-emission vehicles. A heat pump system is one solution to heating the cabin and defrosting the windshield while consuming little energy. The system components consist of an internal heat exchanger, external heat exchanger, electrically driven compressor, electric expansion valve, and refrigerant flow change valves. Cooling capacity was examined by varying vehicle driving conditions and the compressor’s rotational speed. Heating performance for the heat pump system was investigated with various outside air temperatures and compressor rotational speeds. The experimental results using a heat pump system could provide thermal comfort in the cabin with smaller energy consumption than a direct electrical heating system. Heating capacity and air discharge temperature are up to 4.9 kW and 41.7°C, respectively, at an outside air temperature of 0°C and 7000 rpm compressor rotational speed. The power consumption of the heat pump system is about one third that of the electric PTC heating system at the same heating capacity.

This paper presents the experimental study of cabin thermal comfort using a cold storage heat exchanger in a vehicle air-conditioning system. Recent vehicle-applied ISG functions for fuel economy and emission, but when vehicles stop, compressors in the air-conditioning system stop, and the cabin temperature sharply increases, making passengers feel thermal discomfort. This study conducts thermal comfort evaluation in the vehicle, which is applied to a cold storage system for the climate control wind tunnel test and the vehicle fleet road test with various airflow volume rates and ambient temperatures blowing to the cold storage heat exchanger. The experimental results, in the cold storage system, air discharge temperature is 3.1-4.2°C lower than current air-conditioning system when the compressor stops and provides cold air for at least 38 extra seconds. In addition, the blowing airflow volume to the cold storage heat exchanger with various ambient temperature was examined for the control logic of the cold storage system, and in the results, the airflow volume rate is dominant over the outside temperature. For this study, a cold storage system is economically useful to keep the cabin at a thermally comfortable level during the short period when the engine stops in ISG vehicles.

In this paper, the flow pattern of viscoelastic fluids flowing inside a 4:1 planar contraction microchannel was investigated and quantitatively analyzed. A wide range of Weissenberg number flows of poly(ethylene oxide) solutions were observed while maintaining low Reynolds number (0.01 > Re). As the shear rate or fluid elasticity was increased, a transition from steady to unsteady flow was observed. In the steady flow region, the flow pattern was Newtonian-like, progressed to a divergent flow where the upstream flow pattern was distorted due to elasticity, and then a vortex developed at the upstream corners. The vortex, which was stable at first, fluctuated with a certain period as the Weissenberg number increased. The oscillating vortex was symmetric at first and became asymmetric with various patterns. As the elasticity increased further, the vortex randomly fluctuated without any time period. The Lyapunov exponent for the change in vortex size was positive, meaning that the flow was spatially chaotic. This paper systematically analyzed the flow patterns of the elastic fluids in the micro-contraction flow, which included; Newtonian-like flow, divergent flow, oscillating flow with symmetry, oscillating flow with asymmetry, and chaotic flow.

This paper investigates the impact of a three-dimensional (3D) air-conditioning (AC) system on cabin thermal comfort. Current AC systems are dependent on the cooling performance of Heating, Ventilation, and Air-Conditioning (HVAC) systems located inside the front instrument panel and supplying cold air from the front to the rear cabin. This results in a difference in perceived thermal comfort between the front and back seats due to a number of factors, including solar radiation through the windows, blower air path, and individual environmental differences. The 3D AC system was designed to improve the thermal comfort of passengers. In order to simulate the 3D AC system, an auxiliary blower was adapted for rear passengers. A cooling performance test and thermal comfort evaluation were conducted, with the blower at various positions in the cabin. According to the experiment results, four positions of the auxiliary blower showed cooling comfort ratings similar to those of the current HVAC system environment, and the thermal comfort ratings in the 3D AC experiment showed improvement. In other words, 3D AC system can reduce energy consumption, because it can reach the set temperature with less AC system operation.

Hybrid Electtic Vehicles (HEVs) have become one of the solutions to the environmental and fuel-consumption issues in current cars. However HEVs are quite complicated due to their combined power trains which may use both internal combustion engines and electric drive motors. HEVs’ thermal management system is very important for good energy use. Thermal management of HEV batteries, such as Ni-MH or Li-Ion, is especially essential for effective operation under load-drive conditions. Reliable battery operation thermal design is even more important. A variety of battery thermal control modules are currently on the market. In this paper, air cooling types for battery thermal management system have been chosen because of their simplicity, cost effectiveness, and easy applications. The performance of the blower unit as major part of the battery cooling system is studied by experiment and on a numerical basis. A prototype BLDC (brushless DC) motor is made, performance is examined and analyzed, and multi-blade fans are optimized using numerical analysis. The overall efficiency of a prototypr BLDC motor is 72%. Also, the effects of the leading edge angle, trailing edge angle, chord length and chord angle on the performance of the multi-blade fan were investigated numerically for the optimal design by using the FLUENT. Finally, the battery cooling system, characteristics of the torque, static pressure, and airflow volume at each specific rotational speed of the fan are examined and analyzed at blowing system.

This study presented the benefit of the pre-ventilation using solar sunroof with integrated photovoltaic. Recent year, auto-makers make an effort to enhance the fuel efficiency and moreover to clean the cabin passenger's health. Solar energy, one of the alternative energies, adapted in automotive air handling system, in order to pre-ventilation when vehicle parked under the sun in summer. The power generated by a prototype solar sunroof has been used to run blower in a air handing system. And the solar sunroof was installed in a vehicle, and evaluated to find out benefit of the pre-ventilation. The effect of reducing the cabin temperature about 3°C ~ 10°C with 20 ~ 40W power generator from solar sunroof were obtained in the pre-ventilation test. This reduced thermal load can lead to the reduction of air-conditioning operation time than that of current car. Moreover, fuel economy may increase as a results of the short use of the air-conditioning time. Additionally, Total Volatile Organic Compounds in the cabin is reduced maximum 80% than that of the current vehicle.

The flow of viscoelastic fluids in a micro-fabricated 4:1 planar contraction channel was studied through flow visualization. As the Weissenberg number ( Wi ) increased, the flow developed from a Newtonian-like to vortex growth, and the transient start-up flow at high Wi was found to experience all the steady patterns at lower Wi flows. The flow sequence was different depending on the fluids and channel dimensions, however, in all the cases we could reach, the steady patterns at a low Wi flow could be matched 1:1 with the transient patterns at a high Wi flow. The plot of Wi and time when the two sets (transient and steady) were matched showed a clear functional relationship, from which the time–Weissenberg number superposition could be confirmed.

Changes in flow pattern were investigated for a viscoelastic fluid (polyethylene oxide) in various-sized micro-fabricated planar 4:1 contraction channels. The flow pattern changed from a Newtonian-like flow to a flow with a vortex growth region, during which a divergent flow and lip vortex were also observed depending on the elasticity number (El) and aspect ratio. When the aspect ratio was large, the lip vortex was observed only in a limited number of cases, and the flow pattern occurring before the vortex growth was more diverse. When the elasticity number was large, the divergent flow was not observed unlike the cases in which the Elasticity number was small. The flow pattern in the contraction microchannel was found to be diverse and abundant depending on the aspect ratio and elasticity number.

Background: Helicobacter pylori (Hp) infection has previously been thought to account for nearly all chronic gastritis. However, recent studies have suggested that Hp-negative gastritis is common and increasing in prevalence in the United States. The etiology and associated risk factors for Hp-negative gastritis remain uncertain.

Dynamic self-assembly of droplets, regular structure formation of moving deformable objects in a confinement environment is a challenging problem in nonlinear dynamics and engineering patterned structure. In the current work, we investigated how the local kinematic history affects the dynamic self-assembly of picoliter-sized droplets near the expansion regions in microfluidic devices. The local kinematic history was controlled by the shape of the expansion region and characterized using computational fluid dynamics. Sizecontrolled aqueous droplets in light mineral oil were continuously generated at T-junction microchannel and transported toward the expansion region. The fast dynamics of the droplets was tracked using high-speed video microscopy. We found three types of dynamic droplet arrays: 1D, 2D zigzag, and irregular. The orderdisorder transition was associated not only with the droplet size, but also with the controlled local kinematic history, which results in the transient deformation of droplet and droplet-droplet interactions. The present results provide us with insight into the dynamic self-assembly of droplets and could be a useful guide for practical applications of droplet-based microfluidics.

Polymer solutions and melts can exhibit large upstream corner and lip vortices, unstable and diverging flow and an enhanced pressure drop when flowing through a geometry containing a constriction. In the present work, we use a planar microfluidic device to show that the length of the downstream constriction plays an important role in the upstream kinematics and the extra pressure drop. That is, the elastic flow phenomena observed upstream of a constriction during entry flows of polymer solutions are not exclusively a result of the stretching dynamics induced by the converging flow—the downstream relaxation events are, at least, equally important. Flow visualization experiments with semi-dilute solutions of a high molecular weight polymer showed that large stable symmetric vortices could be reduced to highly chaotic asymmetric flow, merely by increasing the length of the constriction—the Reynolds number and elasticity number were both held constant. This was accompanied by a higher extra pressure. These results support the hypothesis that elastic flow instabilities originate downstream of the constriction (at the expansion) and move progressively upstream with time and/or flowrate. These findings may also partly explain the discrepancies commonly observed between the results of entry flow experiments and numerical simulations, in which the downstream geometry is very rarely considered. Lastly, we illustrate how to minimize the occurrence of unstable flow upstream of a constriction, which is a necessary condition for closed microrheometry devices used to characterize low viscosity elastic fluids.

This paper describes a novel integrated time register and arithmetic circuit (TRAC) for time-domain signal processing (TDSP). TRAC has four basic functions: time register, time adder, time subtractor, and time amplifier. One TRAC is able to accept multiple inputs and perform the combination of basic functions. Thus, complex arithmetic operations can be performed synchronously with a TRAC. In a synchronous time-to-digital converter (TDC), a high-gain residue amplifier with the suppressed offset-time component at the output can be implemented by exploiting the advantages of TRAC. The functions of TRAC are with post-layout data simulated in 110nm CMOS technology.