Assist Techniques Research Articles

A Rendezvous Mission to the Second Earth Trojan Asteroid 2020 XL5 with Low-Thrust Multi-Gravity Assist Techniques

As the second of Earth’s Trojan asteroids, 2020 XL5 is worthy of rendezvous and even sample return missions in many aspects. In this paper, a rendezvous mission to Earth’s second Trojan asteroid 2020 XL5 is proposed. However, due to its high inclination and large eccentricity, direct impulsive transfer requires large amounts of fuel consumption. To address this challenge, we explore the benefits of electric propulsion and multi-gravity assist techniques for interplanetary missions. These two techniques are integrated in this mission design. The design of a low-thrust gravity-assist (LTGA) trajectory in multi-body dynamics is thoroughly investigated, which is a complex process. A comprehensive framework including three steps is presented here for optimization of LTGA trajectories in multi-body dynamics. The rendezvous mission to 2020 XL5 is designed with this three-step approach. The most effective transfer sequence among the outcomes involves Earth–Venus–Earth–Venus-2020 XL5. Numerical results indicate that the combination of electric propulsion and multi-gravity assists can greatly reduce the fuel consumption, with fuel consumption of 9.03%, making it a highly favorable choice for this rendezvous mission.

Threshold Selector and Capacitive Coupled Assist Techniques for Write Voltage Reduction in Metal–Ferroelectric–Metal Field-Effect Transistor

We propose device and circuit assist techniques to lower the ferroelectric–metal field-effect transistor (FeMFET) write voltage while lowering the effect of depolarizing field. A bipolar threshold selector (TS) is connected between the intermediate node of a FeMFET and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {SS}}$ </tex-math></inline-formula> , which provides a low-impedance bypass path by triggering an insulator to metallic transition during a write operation. This lowers the voltage drop across MOSFET and reduces the write voltage to ~1.7 V. For further reduction in write voltage, the MOSFET in the FeMFET is utilized as a circuit assist by repurposing it as a capacitive coupling device. It reduces the write voltage to ~1.4 V. During the read mode, TS is in insulating state and does not alter the capacitive voltage divider action. Read is followed by a data-dependent write-back stage to bring the polarization close to retention polarization. During the retention mode, TS acts as a weak bleeder resistor, reducing noise coupling and depolarizing field. TS parameter sensitivity for write voltage reduction along with row hammer effect of the proposed read- and write-back operation is also presented.

Differences in the Peak Inspiratory Flow in Manual Breathing Assist and Rib Springing Techniques

Differences in the Peak Inspiratory Flow in Manual Breathing Assist and Rib Springing Techniques

Write and Read Assist Techniques for SRAM Memories in Nanometer Technology

SRAM cell stability is the primary concern for future technologies due to process variations like threshold voltage and supply voltage scaling etc. The increased effect of process variation and increase in parasitic resistance and capacitance in Nano scale technologies, the lower supply voltages, continuous increase in the size of SRAMs requires additional techniques such as write assist and read assist to improve the write-ability, readability and stability of SRAM memories. In this paper various write and read assist techniques are analyzed with their pros and cons and each technique is explained with their implementation and their impact on write-ability, readability and stability of the SRAM memory. The SRAM bit cell write-ability is very critical at lower voltages. The impact of the write assist technique analyzed across the process, voltage and temperature range. Along with improving the write-ability of the SRAM cell the write assist techniques will impact the performance, power and area of the chip. At lower voltages the noise margin is very crucial for the SRAM cell stability. Read assist techniques help in improving the cell stability and these techniques analyzed across the process, voltage and temperature range. These read assist techniques not only helps the readability and stability of SRAM bit cells but they also will impact the performance, power and area of the chip.

Design of 10T SRAM Cell using Column-Line Assist and DTMOS Techniques

Objective: In this article an SRAM cell based on Column Line Assist (CLA) and DTMOS techniques is proposed. Method/Analysis: The CLA scheme is used to provide a dual path during read and write. The availability of an extra path causes read and write delay to be lesser in case of the proposed design when compared to the conventional 10T SRAM cell. Findings: The use of DTMOS scheme causes the threshold voltage of the MOSFETs to be lower, thereby providing faster switching. Our proposed design is compared to the previously designed conventional 10T SRAM cell (CON 10T). It is found that the proposed design shows 1.91 × increments in read current and 43.3% narrower spread in read current. In terms of read delay, an improvement of 1.68 × is observed. Also, the variability is improved by 70%. The read static noise margin (RSNM) of the proposed design is 0.85 × lesser as compared to the CON10T cell. Novelty/Improvement: The write current and write static noise margin increase by 6.2% and 3 × at VDD= 0.4V.

Eco Assist Techniques through Real-time Monitoring of BEV Energy Usage Efficiency.

Energy efficiency enhancement has become an increasingly important issue for battery electric vehicles. Even if it can be improved in many ways, the driver’s driving pattern strongly influences the battery energy consumption of a vehicle. In this paper, eco assist techniques to simply implement an energy-efficient driving assistant system are introduced, including eco guide, eco control and eco monitoring methods. The eco guide is provided to control the vehicle speed and accelerator pedal stroke, and eco control is suggested to limit the output power of the battery. For eco monitoring, the eco indicator and eco report are suggested to teach eco-friendly driving habits. The vehicle test, which is done in four ways, consists of federal test procedure (FTP)-75, new european driving cycle (NEDC), city and highway cycles, and visual feedback with audible warnings is provided to attract the driver’s voluntary participation. The vehicle test result shows that the energy usage efficiency can be increased up to 19.41%.

Safety of Preprocedural Antiplatelet Medication in Coil Embolization of Ruptured Cerebral Aneurysms at the Acute Stage

Preoperative antiplatelet medication for aneurysm coil embolization during acute subarachnoid hemorrhage (SAH) is not common. However, recent advances in neurointerventional devices make antiplatelet medication necessary for SAH surgery. We tested the hypothesis that preprocedural antiplatelet therapy in the acute stage of SAH prevents complications due to ischemia or induced bleeding. We retrospectively reviewed 35 consecutive ruptured cerebral saccular aneurysms that underwent coiling at our institute. Two hundred milligrams of aspirin and 150 mg of clopidogrel were administered to the patients at least two hours before coiling. Systemic heparinization was given after sheath insertion. Procedure-related thrombus formation on digital subtraction angiography, and clinical evidence of ischemia and procedure-related stroke on CT were reviewed. The median patient age was 69 years. Five males and 30 females were included. Seventy-seven percent of patients were Hunt-Hess grades 1 to 3. Assist techniques were used in 20 cases (57%). We inserted one extracranial internal carotid artery stent, but no intracranial stent. Intraoperative thrombosis occurred in one case (2.9%), with no clinical symptoms. Postoperative cerebrospinal fluid drainage was done in three cases, but we experienced no bleeding complications. Preoperative antiplatelet therapy leads to a low rate of thromboembolic events in coiling during acute stage SAH, and this strategy had no adverse influence on bleeding complications.

SRAM Assist Techniques for Operation in a Wide Voltage Range in 28-nm CMOS

Reducing static random-access memory (SRAM) operational voltage (Vmin) can greatly improve energy efficiency, yet SRAM Vmin does not scale with technology due to increased process variability. Assist techniques have been shown to improve the operation of SRAM, but previous investigations of assist techniques at design time have either relied on static metrics that do not account for important transient effects or make specific assumptions about failure distributions. This paper uses importance sampling of dynamic failure metrics to quantify and analyze the effect of different assist techniques, array organization, and timing on Vmin at design time. This approach demonstrates that the most effective technique for reducing SRAM Vmin is the negative bitline write assist, resulting in a Vmin of 600 mV for a 28-nm LP process in the typical corner.

Breathing Assist Techniques from Japan

Breathing Assist Techniques from Japan

Circulatory Assist Techniques After Cardiomyoplasty

Cardiomyoplasty, in spite of recent improvements, remains a high risk operation. The early postoperative period is sometimes very critical, even for patients selected from preoperative New York Heart Association functional class IV. During the surgical period, poor hemodynamics may be responsible for early death, as well as influence latissimus dorsi muscle long-term viability. Circulatory assist, including pharmacologic support with enoximone, intraaortic balloon counterpulsation (IABP), and ventricular assist devices (VAD), may be needed. From February, 1993 to September, 1994, 14 clinical dynamic cardiomyoplasty procedures were performed using the Medtronic (Minneapolis, MN) system at Hôpital La Timone, Marseille, France. Eight patients suffered from early and severe postoperative heart failure. Enoximone was used in three patients and IABP in five patients. Two days after cardiomyoplasty, one of the IABP patients required an implantable left VAD (Thermocardio Systems, Woburn, MA) as a bridge to cardiac transplantation. Overall hospital mortality was 7%. The authors studied the preoperative clinical data and surgical techniques to find specific risk factors that could have influenced postoperative events. Another aim of this study was to evaluate long-term benefits in these particular patients. Results showed that cardiomyoplasty patients may require complex means to overcome postoperative hemodynamic failure, but without necessarily poor long-term results. This should be an important step in improving future patient selection.

Circulatory Assist Techniques in Cardiogenic Shock: Metabolic Aspects

Assisted circulation in severe cardiogenic shock was evaluated using a reservoir and a single pump without an oxygenator in 88 dogs. Study groups included: no treatment, substrates only (cysteine, ribose), nitroprusside, left ventricular (LV) + right atrial (RA) bypass + substrates, LV + RA bypass, left atrial (LA) + RA bypass, LA bypass, LV bypass, LV + RA + fluosol. Metabolic studies of O2 consumption, acid and alkaline phosphatase, lactate, creatine phosphokinase (CPK), myocardial depressant factor (MDF), and tissue adenosine triphosphate (ATP) were done in the course of 4-hour treatment periods followed by 2-hour observation periods. Best survival at 4-hour and 6-hour levels were achieved in LV + RA bypass. Cysteine and ribose reduced survival when added to the pump supported (LV + RA bypass) group. Cysteine/ribose improved survival over the no treatment group. O2 consumption increased significantly in the groups with best survival but remained unchanged from control or shock levels when cysteine/ribose were added. Unusually high levels of CPK, acid and alkaline phosphatase, and MDF occurred in both groups receiving cysteine/ribose, indicating significant organ damage correlating with poor survival. Lactate levels were less predictive. Heart tissue ATP levels were higher in groups with good survival. Liver ATP levels were lower in high survival groups. Lung ATP did not differ between groups.

Mechanical circulatory assist techniques in the treatment of cardiogenic shock

Five techniques of mechanical cardiovascular assistance have been evaluated as therapeutic adjuncts in the treatment of cardiogenic shock. Cardiac support by mechanical direct ventricular assistance may be useful when defibrillation in open-chest resuscitation cannot be accomplished in order that defibrillation be later attempted under more corrected conditions. This technique has the advantage of exposing blood only to natural endothelium but has the disadvantage of requiring thoracotomy. Complete diversion of the cardiac output from the left ventricle by left ventricular bypass should be beneficial in the treatment of left ventricular failure. However, any degree of partial left ventricular bypass is probably detrimental. Venoarterial bypass is best applied in the treatment of acute right heart failure in the presence of a normal left ventricle. Its use in right heart failure after acute pulmonary embolism is strongly recommended. Synchronous arterioarterial pumping should be beneficial in the treatment of cardiogenic shock secondary to left ventricular failure in the absence of aortic insufficiency. The intraaortic balloon and extramural pressure techniques hold promise as simple and reliable methods. Venoarterial phased pulsatile partial bypass seems indicated for catastrophic conditions when total circulatory collapse is unresponsive to resuscitative measures.