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This paper analyzed the effects of setback micro-springs on a MEMS safety and arming (S&A) device. To make up for defects related to current methods of obtaining the elastic coefficients of micro-springs, a computational formula for the elastic coefficients of S-shaped micro-springs was developed in accordance with Castigliano’s second theorem and Hooke’s law and verified for three types of setback micro-springs with different structures through finite element simulations and a self-designed testing system for the elastic coefficients of micro-springs. The testing values and the simulation values were in good agreement with the theoretical values. The results indicate that the precise measurement and calculation of the elastic coefficients of micro-springs in the transverse, longitudinal and vertical directions can be realized with the method presented in this paper. For the S-shaped setback micro-spring, the elastic coefficient in the transverse direction is the smallest and the most prone to fracture and plastic deformation. In the design of MEMS S&A devices, priority should be given to applying the deformation of the micro-spring in the longitudinal and vertical directions.

Mechanical equipment fault detection is critical in industrial applications. Based on vibration signal processing and analysis, the traditional fault diagnosis method relies on rich professional knowledge and artificial experience. Achieving accurate feature extraction and fault diagnosis is difficult using such an approach. To learn the characteristics of features from data automatically, a deep learning method is used. A qualitative and quantitative method for rolling bearing faults diagnosis based on an improved convolutional deep belief network (CDBN) is proposed in this study. First, the original vibration signal is converted to the frequency signal with the fast Fourier transform to improve shallow inputs. Second, the Adam optimizer is introduced to accelerate model training and convergence speed. Finally, the model structure is optimized. A multi-layer feature fusion learning structure is put forward wherein the characterization capabilities of each layer can be fully used to improve the generalization ability of the model. In the experimental verification, a laboratory self-made bearing vibration signal dataset was used. The dataset included healthy bearings, nine single faults of different types and sizes, and three different types of composite fault signals. The results of load 0 kN and 1 kN both indicate that the proposed model has better diagnostic accuracy, with an average of 98.15% and 96.15%, compared with the traditional stacked autoencoder, artificial neural network, deep belief network, and standard CDBN. With improved diagnostic accuracy, the proposed model realizes reliable and effective qualitative and quantitative diagnosis of bearing faults.

Background Small compound oridonin acts as an effective anti-tumor agent used for a wide variety of human malignancies, while the antitumor efficacy and molecular mechanism of oridonin against bladder cancer remains unclear. Methods Four independent cohorts of bladder cancer were employed to assess the correlation between netrin-1 expression and progression and prognosis of bladder cancer. Clinical potential of netrin-1 as a biomarker and oridonin-mediated netrin-1-targeting anti-tumor mechanism were investigated by QRT-PCR, Western blot and ELISA. Regulatory mechanisms of Netrin-1 were investigated by luciferase reporter assay and Western blot. The EJ-inoculated nude mice xenograft model was used for the in vivo study. Results High expression of netrin-1 was significantly correlated with a poor overall survival in three independent bladder cancer cohorts. Urinary netrin-1 level was significantly elevated in bladder cancer patients correlating with tumor invasion and grade. Netrin-1 promoted cell proliferation, tumorsphere-forming, migration and invasion in bladder cancer cells. Oridonin treatment strikingly suppressed these malignant phenotypes and induced cell death in TCC cell lines and murine xenografts. Oridonin markedly decreased netrin-1 through inhibiting NF-κB transcriptional activity and shortening the half-life of NTN1 mRNA via inducing IRE1α, resulting in repression of its downstream signaling. Conclusions Together, these results strongly suggest that netrin-1 promotes the progression of bladder cancer, and acts as a potential urinary biomarker for the diagnosis as well as the prediction of the tumor progression. Oridonin exerts its strong anti-tumor activity against the invasive bladder cancer by suppressing netrin-1 mRNA production and stability.

In this work, the organic light-emitting diodes (OLEDs) based on Alq3 are fabricated. In order to make clear the transport mechanism of carriers in organic light-emitting devices at low temperature, detailed electroluminescence transient response and the current-voltage–luminescence (I–V–L) characteristics under different temperatures in those OLEDs are investigated. It founds that the acceleration of brightness increases with increasing temperature is maximum when the temperature is 200 K and it is mainly affected by the electron transport layer (Alq3). The MoO3 injection layer and the electroluminescent layer have great influence on the delay time when the temperature is 200 K. Once the temperature is greater than 250 K, the delay time is mainly affected by the MoO3 injection layer. On the contrary, the fall time is mainly affected by the electroluminescent material. The Vf is the average growth rate of fall time when the temperature increases 1 K which represents the accumulation rate of carriers. The difference between Vf caused by the MoO3 injection layer is 0.52 us/K and caused by the electroluminescent material Ir(ppy)3 is 0.73 us/K.

This paper studies the aerodynamic characteristics of the composite motion of the wing during the flight of the bionic flapping wing. The dynamic hybrid mesh technique is used to solve the Nave Stokes (N-S) equation, and the changes of the lift resistance generated by the wing under different flapping amplitude, flapping frequency and chord torsion angle parameters are analyzed. By analyzing the aerodynamic efficiency of the wing, the optimal motion parameters of the flapping wing are obtained, which provides a theoretical basis for the design of the flapping bionic aircraft.

Micro inertial switches are widely used in airbags, accessories and military weapons. SU-8 photoresist and electroforming based UV-LIGA process is an effective way to fabricate inertial switches. However, during the fabrication, the high stress in the SU-8 layers often causes them to detach from the substrate, which results in fabrication failure. To solve the detachment problem of SU-8 layers, a novel method was presented in this paper to release the internal stress in SU-8 layers by decreasing the area of electroforming layers. ANSYS simulation study was performed to verify the stress reduction effect of this method. The simulation and experiment results showed that stress in SU-8 layers can be reduced effectively. By using this method, a multi-scale inertial switch with ultra-high aspect ratio 17:1 was fabricated successfully. The overall size of the inertial switch is 14 × 11 × 0.6 mm. The inertial switch is fabricated by multi-layer UV-LIGA process. Fabrication error of the process is estimated in this paper. The stress reduction method and error estimate method presented in this paper can provide help to the fabrication of micro metal devices with large area and high aspect ratio.

For single non-uniform surface compound eyes cannot achieve zoom imaging, resulting in poor imaging and other issues, a new type of aspherical artificial compound eye structure with variable focal length is proposed in this paper. The structure divides the surface compound eye into three fan-shaped areas, and different focal lengths of the micro-lens in different area make the artificial compound eye zoom in a certain range. The focal length and size of the micro-lens are determined by the area and the location of the micro-lens. The optimization of aspherical array of the micro-lens is calculated and the spherical aberration in each area is reduced to one percent of the initial value. Through simulation analysis, the designed artificial compound eye structure can realize the focal length adjustment, and effectively reduce the problem of the poor imaging quality of the curved compound eye edge. As a result, the aspherical artificial compound eye sample with the number of eyes of n=61 and the diameter of the base of 8.66mm was prepared using the molding method. The mutual relationship between the eyes of the child was calibrated and a mathematical model for the simultaneous identification of multiple sub eyes was established. An artificial compound eye positioning experimental system with the error value less than 10% was set up through a number of micro-lens capture target point settlement coordinates.

The Omni-directional impact MEMS switch was designed and characterized for the purpose of impact sensing. In order to turn on the circle reliably, the connect time should be long enough, the structure of flexible electrode was designed to extend the holding time. The structure consists of electrode A and B, electrode A is the sensing mass simultaneously, the sensing mass is suspended by helix cantilever that is fixed to the pedestal, the outer ring is the electrode B, which is suspended by helix cantilever that is fixed to the outer frame. Between the two electrodes, there is a gap, the gap separates electrode A and B, thereby keeping the switch in the open state. The distortion during the impact process extended the contact time. The dynamics of the switch is simulated, the simulation results show that the response time of the switch is 0.135ms, it is short enough, and the contact time which is also called holding time is about 20, the extended time make the switch turn on more reliably. These results satisfy the required specifications for the ammunition systems. DOI: http://dx.doi.org/10.11591/telkomnika.v11i5.2473

In this paper, a novel MEMS inertial switch is designed and characterised for the purpose of crash sensing for ammunition systems in which high-speed response is required for triggering the detonator. In order to keep the same sensitivity in different direction, the structure of an annular proof-mass suspended by four serpentine flexures is designed. The motion of the inertial switch is analysed by dynamic simulation, the simulation results show that the response time is 0.142 ms and the contact time of the switch is about 5 us under the 700 g threshold acceleration. It illustrates that the response time is short enough and the impact time satisfy the ask. The von-mises stress of the structure is calculate, the maximum stress occurs in the serpentine flexures, the value is 60.61 MPa, much less than the yield strength of the silicon, the switch can be used time after time. The static behaviour of the serpentine flexures is researched, and the width of the serpentine flexure is determined as the most important factor to the threshold acceleration. With the width of the serpentine flexure increasing, the threshold of the switch will increase, and the response time of the inertial switch will decrease.