Enhancing the Shock Response Performance of Micromachined Silicon Resonant Accelerometers by Electrostatic Active Damping Control

This paper presents a micromachined silicon resonant accelerometer based on electrostatic active damping control, which can improve the shock response performance of the accelerometer. In the accelerometer, an electrostatic active damping structure and damping control circuit are designed to improve the equivalent damping coefficient of the system. System-level Simulink modeling and simulation of the accelerometer with an electrostatic active damping closed-loop control link were carried out. The simulation results indicate that the system can quickly return to normal output without an obvious vibration process after the shock. The fabricated and packaged accelerometer was connected to an external test circuit for shock performance testing. The stabilization time of the accelerometer after a 100 g, 3–5 ms half-sine shock was reduced from 19.8 to 5.6 s through use of the damping control. Furthermore, the change in deviation before and after the shock without damping control was 0.8197 mg, whereas it was 0.1715 mg with damping control. The experimental results demonstrate that the electrostatic active damping control can effectively improve the dynamic performance of the micromachined silicon resonant accelerometer.

Global Health Security Preparedness and Response: An Analysis of the Relationship between Joint External Evaluation Scores and COVID-19 Response Performance

ObjectivesThe COVID-19 pandemic has highlighted the importance and complexity of a country’s ability to effectively respond. The Joint External Evaluation (JEE) assessment was launched in 2016 to assess a country’s ability to prevent, detect and respond to public health emergencies. We examined whether JEE indicators could be used to predict a country’s COVID-19 response performance to tailor a country’s support more effectively.DesignFrom April to August 2020, we conducted interviews with Centers for Disease Control and Prevention country offices that requested COVID-19 support and previously completed the JEE (version 1.0). We used an assessment tool, the ‘Emergency Response Capacity Tool’ (ERCT), to assess COVID-19 response performance. We analysed 28 ERCT indicators aligned with eight JEE indicators to assess concordance and discordance using strict agreement and weighted kappa statistics. Generalised estimating equation (GEE) models were used to generate predicted probabilities for ERCT scores using JEE scores as the independent model variable.ResultsTwenty-three countries met inclusion criteria. Of the 163 indicators analysed, 42.3% of JEE and ERCT scores were in agreement (p value=0.02). The JEE indicator with the highest agreement (62%) was ‘Emergency Operations Center (EOC) operating procedures and plans’, while the lowest (16%) was ‘capacity to activate emergency operations’. Findings were consistent with weighted kappa statistics. In the GEE model, EOC operating procedures and plans had the highest predicted probability (0.86), while indicators concerning response strategy and coordination had the lowest (≤0.5).ConclusionsOverall, there was low agreement between JEE scores and COVID-19 response performance, with JEE scores often trending higher. JEE indicators concerning coordination and operations were least predictive of COVID-19 response performance, underscoring the importance of not inferring country response readiness from JEE scores alone. More in-depth country-specific investigations are likely needed to accurately estimate response capacity and tailor countries’ global health security activities.

Improving the Response Performance of Anti-Surge Control Valve for Gas Compressors

Anti-surge control valves are used for the protection of gas compressors by opening to relief sudden pressures (surge) which could damage the compressor internals. It is of great importance that the response of the anti-surge valves to surge detection is swift and within a few seconds since a little delay could cause catastrophic damages to the compressor it is meant to protect. In this paper, a design modification was done on an existing anti-surge valve to improve its response time. The modified system was designed and implemented, installed, and commissioned on a mixed refrigerant compressor. The modified system was tested, and the response performance was recorded. Results obtained showed average percentage improvement of 86% to that of the initial system. Also, the response performance of the modified system was less than 3 seconds as compared to the initial set-up which averages 9 seconds. This is indeed a great improvement in comparison to the initial system.

A Hybrid-Mode LDO Regulator with Fast Transient Response Performance for IoT applications

A hybrid-mode low-drop out (LDO) voltage regulator with fast transient response performance for IoT applications is proposed in this paper. The proposed LDO regulator consist of two sections. First section is an analog regulator which includes a folded cascode operational amplifier to achieve good PSRR. Second section is current DAC and detectors whitch includes a cource current DAC, sink current DAC, undershoot detectors, and overshoot detectors. The current DAC and detectors are designed to obtain a low drop out and fast transient response. The proposed hybrid-mode LDO voltage regulator has been designed, simulated and layouted in Cadence using TSMC 90 nm CMOS technology. The input range of the LDO regulator is 1.2–2.0 V, and it can produces an output voltage of 1.2V. The LDO regulator achieves 58uA quiescent current, -69 PSRR @ 1 KHz noise frequency and an output voltage drop of around 60mV for a load current step of 100 mA. The final design occupies approximately 0.09 mm2.

Synthesis of Betaine Copolymer for Surface Modification of Cotton Fabric by Enhancing Temperature-Sensitive and Anti-Protein Specific Absorption Performance

The growth and reproduction of microorganisms on fabrics could not only affect the wearability of textiles but also cause harm to human health, and it is an important problem that should be solved to reduce the adsorption and growth of microorganisms on the surface of the fabric. A series of ω-vinyl betaine copolymers were synthesized by catalytic chain transfer polymerization (CCTP) and were modified by mercapto-vinyl click chemistry to synthesize silane-modified betaine copolymers, which were used to treat the cotton fabric. The hydrophilic–hydrophobic transition performance and anti-protein specific adhesion performance of cotton fabric with the betaine copolymer were systematically investigated. The copolymer was confirmed to be successfully finished on the cotton fabric via 1H–NMR and FTIR. The cotton fabric, which was treated by the betaine copolymer, presented temperature response performance in the range of 30–55 °C and had excellent anti-protein adsorption performance. The treated fabric had the best temperature-sensitive and anti-protein specific absorption performance among all the specimens when the mass fraction of G06B in DMAPS was 6 wt.%.

Research on Stability of Sand Core Handling Robot System Based on PID Control

When an industrial robot uses a gripper with half hardness and flexibility to carry a hollow sand core, mechanical vibration will cause the gripper to grasp the sand core unsteadily or cracks in the sand core due to excessive pressure. In this paper, the mathematical model is constructed based on the elements such as gripper structure, clamping pressure and mechanical vibration, the system stability is analyzed, the PID controller is added for correction, the parameter values of Kp, Ti and Td are set by Ziegler-Nichols method, the transfer function of PID controller is obtained, and then the corrected system function is calculated. The dynamic response performance of the system is simulated and analyzed by Matlab / Simulink, the parameters in the PID controller are adjusted, and the overshoot of the system is reduced from 85% to 25%, which effectively reduces the impact of mechanical vibration interference on the sand core and realizes the optimal control of the system.

Transient Response Performance Test on Aftermarket Motorcycle Rear Suspension in Indonesia

Modification parts are found in Indonesia, one of which is suspension. This paper proves which after-market suspension has the best performance. These three suspensions were tested with a transient response with a test instrument that has an excitation height of 30 mm with a shaft rotational speed of 322 rpm. The observed responses are displacement and settling time. The test results without the addition of mass obtained a displacement of 25 mm for Aspira, 39 mm for AHM and 39 mm for Combiz. The addition of 30 kg mass resulted in 29 mm for Aspira, 38 mm for AHM and 23 mm for Combiz. Settling time without adding mass 1 s for Aspira and 1.2 s for AHM and 0.9 s for Combiz. With the addition of 30 kg mass obtained settling time of 1.3 s for Aspira, 1 s for AHM and 0.7 s for Combiz.