Low-consumption stepper motor controller with real-time target position change responsiveness based on field programmable gate array.

In response to the demand for low resource consumption, parallel control, and real-time response to target position changes in precision measurement and manufacturing of multi-axis stepper motor controllers, this paper proposes a field programmable gate array-based method for generating trapezoidal velocity profiles and pulse generation, which can easily keep parallelism and independence during multi-axis control. By avoiding using multiplication and division, this controller not only reduces resource consumption but also enhances the pulse output frequency. To address the real-time responsiveness of the velocity profile generation algorithm to changes in the target position during the control process, the algorithm introduces a novel real-time comparative state transition logic for speed control, which makes it capable of adjusting the acceleration within a single clock cycle, enabling its application in scenarios that require higher levels of real-time performance. Finally, the designed controller is applied to a four-axis positioning system for performance validation.

Research Progress of Graphene Nano-Electromechanical Resonant Sensors-A Review.

Graphene nano-electromechanical resonant sensors have wide application in areas such as seawater desalination, new energy, biotechnology, and aerospace due to their small size, light weight, and high sensitivity and resolution. This review first introduces the physical and chemical properties of graphene and the research progress of four preparation processes of graphene. Next, the principle prototype of graphene resonators is analyzed, and three main methods for analyzing the vibration characteristics of a graphene resonant sheet are described: molecular structural mechanics, non-local elastic theory and molecular dynamics. Then, this paper reviews research on graphene resonator preparation, discussing the working mechanism and research status of the development of graphene resonant mass sensors, pressure sensors and inertial sensors. Finally, the difficulties in developing graphene nano-electromechanical resonant sensors are outlined and the future trend of these sensors is described.

Yes-associated protein reacts differently in vascular smooth muscle cells under different intensities of mechanical stretch.

Vascular smooth muscle cells (VSMCs) are stromal cells of the vascular wall and are continually exposed to mechanical signals. The loss of VSMCs is closely related to the occurrence of many vascular diseases, such as aortic aneurysms and aortic dissection. The proliferation and apoptosis of VSMCs are mechanically stimulated. Yes-associated protein (YAP), one of the core components of the Hippo pathway, plays a key role in the response of VSMCs to mechanical signals. In this study, we tested the impact of different intensities of mechanical stretch on the proliferation and apoptosis of VSMCs, as well as YAP. We tested VSMCs' proliferation and apoptosis and YAP reaction via immunocytochemistry, western blotting, CCK-8 and flow cytometric analysis. We found that 10% elongation could increase the phosphorylation of YAP and prevent it from entering the nucleus, as well as inhibit cell proliferation and promote apoptosis. However, 15% elongation reduced YAP phosphorylation and promoted its nuclear entry, thereby promoting cell proliferation and inhibiting apoptosis. Accordingly, YAP knockdown suppressed the phenotype of VMSCs induced by 15% elongation. Taken together, YAP regulates proliferation and apoptosis of VSMCs differently under different intensity of mechanical stretch. Mechanical stretch with appropriate intensity can promote the proliferation and inhibit apoptosis of VSMCs by activating YAP.

Modeling and Analysis of a SiC Microstructure-Based Capacitive Micro-Accelerometer.

In this study, a comb-type capacitive accelerometer based on a silicon carbide (SiC) microstructure is presented and investigated by the finite element method (FEM). It has the advantages of low weight, small volume, and low cross-coupling. Compared with silicon(111) accelerometers with the same structure, it has a higher natural frequency. When the accelerometer vibrates, its resistive force consists of two main components: a viscous damping and an elastic damping force. It was found that viscous damping dominates at low frequency, and elastic damping dominates at high frequency. The second-order linear system of the accelerometer was analyzed in the time-frequency domain, and its dynamic characteristics were best when the gap between the capacitive plates was 1.23 µm. The range of this accelerometer was 0-100 g, which is 1.64 times that of a silicon(111) accelerometer with the same structure. In addition, the accelerometer could work normally at temperatures of up to 1200 °C, which is much higher than the working temperatures of silicon devices. Therefore, the proposed accelerometer showed superior performance compared to conventional silicon-based sensors for inertial measurements.

An Ultrahigh-Sensitivity Graphene Resonant Gyroscope.

In this study, a graphene beam was selected as a sensing element and used to form a graphene resonant gyroscope structure with direct frequency output and ultrahigh sensitivity. The structure of the graphene resonator gyroscope was simulated using the ANSYS finite element software, and the influence of the length, width, and thickness of the graphene resonant beam on the angular velocity sensitivity was studied. The simulation results show that the resonant frequency of the graphene resonant beam decreased with increasing the beam length and thickness, while the width had a negligible effect. The fundamental frequency of the designed graphene resonator gyroscope was more than 20 MHz, and the sensitivity of the angular velocity was able to reach 22,990 Hz/°/h. This work is of great significance for applications in environments that require high sensitivity to extremely weak angular velocity variation.

A Compensation Method for Nonlinear Vibration of Silicon-Micro Resonant Sensor.

A compensation method for nonlinear vibration of a silicon micro resonant sensor is proposed and evaluated to be effective through simulation and experimental analysis. Firstly, the parameter characterization model of the silicon micro resonant sensor is established, which presents significant nonlinearity because of the nonlinear vibration of the resonant beam. A verification circuit is devised to imitate the nonlinear behavior of the model by matching the simulation measurement error of the frequency offset produced by the circuit block with the theoretical counterparts obtained from the model. Secondly, the principle of measurement error compensation is studied, and the compensation method dealing with nonlinear characteristics of the resonant beam is proposed by introducing a compensation beam and corresponding differential operations. The measurement error, compensation rate, and measurement residual between the two scenarios that use single beam and double beams, respectively, are derived and are compared with their simulation and experimental counterparts. The results coincide with the predicted trend, which verifies the effectiveness of the compensation method.

Prevention of Vascular Anastomotic Stenosis With 2-Octylcyanoacrylate.

Although conventional microvascular anastomoses are well-studied, postoperative anastomotic stenoses remain a common surgical complication. The use of 2-octylcyanoacrylate to stabilize vascular anastomoses using a rabbit anastomosis model was investigated. A carotid artery anastomosis model was established in 20 New Zealand rabbits (2.5-3.0 kg): 10 underwent conventional anastomosis surgery with sutures only, while 10 underwent suture ligation, followed by the application of 2-octylcyanoacrylate. Vascular patency and pulse strength were observed after adhesive solidification. The artery diameter was measured preoperatively and at 5 minutes, 2 weeks, and 4 weeks postoperatively. An angiography was performed at 4 weeks postoperatively. Hyperplasia and the induced nitric oxide synthase (iNOS) content of the intima and media layers from the anastomotic stoma were assessed using immunohistochemistry. The artery inner diameter of experimental group decreased at each time point postoperatively (1.686 ±â€Š0.066 cm; 1.656 ±â€Š0.069 cm; 1.646 ±â€Š0.074 cm) (P ≤ 0.01). At 4 weeks postoperatively, the intima and the media around the anastomosis was both significantly thinner in the experimental group (13.21 ±â€Š0.84 µm; 234.86 ±â€Š13.84 µm) than in the control group (17.06 ±â€Š0.96 µm; 279.88 ±â€Š34.22 µm) (P < 0.05). At 4 weeks postsurgery, intravascular iNOS expression was increased in both groups but was higher in the experimental group (82.5% versus 47.5%). The above results indicated that 2-octylcyanoacrylate adhesive can inhibit stenosis of vascular anastomoses.

[Testing System for Biomechanical Properties of Bone].

A novel testing system is designed to simulate the mechanical performance and evaluate the biomechanical properties of the bone and the corresponding bone fixator. It is mainly composed of movement platform and servo motor system, sensors and hardware circuit system and software system. In order to prove the feasibility of the design, on the basis of the calibration for the force sensor, the fatigue experiment is carried out using the tibia of the sheep. It is concluded from the result that under the condition of 1 Hz in frequency, 50 kg in loading force and 18 000 cycles, the bone fixator can be still in good condition, which proves the feasibility of the design.

[Development on Early Treatment Technique of Vascular Injury in Wartime].

In the background of the high incidence of vascular injury in wartime, this paper introduces the characteristics of vascular injury in war environment and the development of early treatment technique of vascular injury applied in wars since World War Ⅱ. Then, the advantages and limitations of various treatment techniques are also analyzed. Finally, The development of technology and research direction are summarized and prospected.

[Development of Wound Quick Closing Device].

Complex and huge wound closure is a key step in pre hospital emergency care. Wound closure can effectively reduce the loss of blood and fluid inpatients before arriving hospital. Also, it has important significance to save the lives of patients. In this paper, a new type of wound closure device is developed, which is used for the rapid closure of complex and huge wound. Firstly, based on the detailed introduction of the structure working principle, the finite element simulation technology is adopted to analyze the stress of the structure. The results show that the stress of the structure has not beyond the allowable stress of the material. On the basis of this, the experiment was carried out in vitro. Test results show that the closure device operating time is 18.24 s and the minimum penetration of the skin force is 4.08 kg. The closure device can resist the horizontal tension of 1.53 kg and vertical tension of 2.25 kg. It also has good sealing performance and meets the design requirements. The results show that the device designed is reasonable, which can be quickly and effectively to achieve closure of the wound.

[Testing Equipment on Vascular Mechanical Properties].

The vascular mechanical parameters are important indicators for human vascular and they play important roles in clinical research. This paper developed a new vascular mechanical properties testing system. This system not only realizes the tensile rupture test in one dimensional, but also the reciprocating tensile test for vascular, which provides more comprehensive experimental data and theoretical basis for the study of human vascular. The system consists of three parts: the mechanical platform, hardware circuit and upper computer system. The mechanical platform transforms the rotation movement of motor into linear movement via the structure of bal screw. And the bal screw and tension sensor are connected, which is used for mechanical data reading. The displacement data is col ected by displacement sensor. Experiments show that the accuracy is better than 0.292%, and could meet the demand of the testing of vascular biomechanical characteristics.

Liquid sinusoidal pressure measurement by laser interferometry based on the refractive index of water.

A new method with laser interferometry is used to enhance the traceability for sinusoidal pressure calibration in water. The laser vibrometer measures the dynamic pressure based on the acousto-optic effect. The relation of the refractive index of water and the optical path length with the pressure's change is built based on the Lorentz-Lorenz equation, and the conversion coefficients are tested by static calibration in situ. A device with a piezoelectric transducer and resonant pressure pipe with water is set up to generate sinusoidal pressure up to 20 kHz. With the conversion coefficients, the reference sinusoidal pressure is measured by the laser interferometer for pressure sensors' dynamic calibration. The experiment results show that under 10 kHz, the measurement results between the laser vibrometer and a piezoelectric sensor are in basic agreement and indicate that this new method and its measurement system are feasible in sinusoidal pressure calibration. Some disturbing components including small amplitude, temperature change, pressure maldistribution, and glass windows' vibration are also analyzed, especially for the dynamic calibrations above 10 kHz.

Theory and experiment research for ultra-low frequency maglev vibration sensor.

A new maglev sensor is proposed to measure ultra-low frequency (ULF) vibration, which uses hybrid-magnet levitation structure with electromagnets and permanent magnets as the supporting component, rather than the conventional spring structure of magnetoelectric vibration sensor. Since the lower measurement limit needs to be reduced, the equivalent bearing stiffness coefficient and the equivalent damping coefficient are adjusted by the sensitivity unit structure of the sensor and the closed-loop control system, which realizes both the closed-loop control and the solving algorithms. A simple sensor experimental platform is then assembled based on a digital hardware system, and experimental results demonstrate that the lower measurement limit of the sensor is increased to 0.2 Hz under these experimental conditions, indicating promising results of the maglev sensor for ULF vibration measurements.

[Portable lung function parameters testing system based on DSP].

Lung function monitoring is a critical technique for clinical medicine. Currently, the lung function testing devices used in our domestic hospitals are both expensive and bulky. A portable and accurate lung function parameters testing system is highly desired and is proposed in this paper. The hardware of the system is based on DSP technology. The breathing passage is designed with an aim suitable for the breathe and signal detection. We use the direct detection method to detect the gas flow, the breathing passage pressure and the breathing time. Thanks to the powerful data processing ability and the high operation speed of the DSP, breathing signals can be easily analyzed. Thus, several lung function parameters of clinical significance can be obtained. Experiments show that the accuracy of the system is better than 3%, and could meet the demand of the lung function testing.

[Development on measuring method for the parameters of orthopaedic biomechanics].

This paper introduces the development on the research of measuring theory for orthopaedic biomechanics in detail. Then, the measuring method and corresponding measuring device are also mentioned. Advantages, disadvantages and development for the device are also introduced. Finally, the research prospect for it is introduced.

[A new kind of minimally invasived external fixator for orthopaedics fabricated with quick casting method].

OBJECTIVE: A new kind of external fixator for orthopaedics is designed in order to overcome the shortcomings of high weight, hard to operate and high degree of hurt for the conventional external fixator. METHODS: The quick casting method is used to realize fast shaping, and FEM (Finite Element Method) is used to verify the practicability of the design. RESULTS: In order to verify the correctness of the design, FEM is used to simulate it. It is concluded from the simulated result that the biggest relative displacement between the borders of the separated bones is just 0.37 mm, which is much less than the requested value 1 mm. This fits the request to cure the patients whose bones are broken and shows the correctness of the design. Finally, ten sheep are used as specimen to verify the feasibility of the design. It is concluded from the X ray sketches of 2 weeks, 4 weeks and 8 weeks that there is no relative displacement happened between the border of the broken bone and the bone is well cured. CONCLUSIONS: This kind of device is feasible to cure the broken bones and the design scheme can be used as the final treatment means.