Search

Asteroid anchoring is the premise for the spacecraft to conduct in-situ scientific exploration on the surface of a weak gravitational asteroid. There is not any precedent for successful anchoring on the asteroid surface all over the world. Ultrasonic drill actuated by the piezoelectric ceramic is especially suitable for drilling on the surface of a weak gravitational asteroid, showing outstanding advantages such as low power consumption, low required drilling pressure and wide temperature range. In order to solve the technical problem of anchoring, a novel anchoring device based on multiple ultrasonic drill cross-drilling geometric force closure is proposed. Firstly, the structure and working principle of the anchoring device are introduced. Then the EDEM software based on the Discrete Element Method is used to simulate the influencing factors of the anchoring force. Finally, the effectiveness of the anchoring device is proved by experiments. The results show that the ultrasonic drill is effective for the anchoring device; the anchoring device can provide an anchoring force of 60–250 N for the spacecraft; its structure is simple, compact and adaptable.

The large-scale application of new technologies such as cloud computing in power supply companies makes the mode of traditional power security zones cannot efficiently support the existing business. A simplified interaction protocol of crossing security zones is proposed based on the TCP, which encapsulate the file transfer protocol in the base of isolation devices. It unifies the exchange interface between the production & control zone and the management & information zone, and accord with the transmission modes of request/reply and subscription/publication. Multi-channel data transmission in isolation devices is implemented by multi-thread technology. It established data confirmation mechanism by priority control in crossing security zones. It implemented high reliability of transmission between forward & reverse isolation devices. Finally, it gives process and results of verification through comparing. The method helps to improve the quality of data sharing for application systems crossing different security zones.

Background. Nonsmall cell lung cancer (NSCLC) is the most common type of lung cancer, and the majority of NSCLC patients are diagnosed at the advanced stage. Chemotherapy is still the main treatment at present, and the overall prognosis is poor. In recent years, immunotherapy has developed rapidly. Immune checkpoint inhibitors (ICIs) as the representative have been extensively applied for treating various types of cancers. Tumor mutation burden (TMB) as a potential biomarker is used to screen appropriate patients for treatment of ICIs. To verify the predictive efficacy of TMB, a systematic review and meta-analysis were conducted to explore the association between TMB and ICIs. Method. PubMed, EMBASE, Cochrane Library, and son on were systematically searched from inception to April 2020. Objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) were estimated. Results. A total of 11 studies consisting of 1525 nonsmall cell lung cancer (NSCLC) patients were included. Comparison of high and low TMB: pooled HRs for OS, 0.57 (95% CI 0.32 to 0.99; P = 0.046 ); PFS, 0.48 (95% CI 0.33 to 0.69; P < 0.001 ); ORR, 3.15 (95% CI 2.29 to 4.33; P < 0.001 ). Subgroup analysis values: pooled HRs for OS, 0.75 (95% CI 0.29 to 1.92, P = 0.548 ) for blood TMB (bTMB), 0.44 (95% CI 0.26 to 0.75, P = 0.003 ) for tissue TMB (tTMB); for PFS, 0.54 (95% CI 0.29 to 0.98, P = 0.044 ) and 0.43 (95% CI 0.26 to 0.71, P = 0.001 ), respectively. Conclusions. These findings imply that NSCLC patients with high TMB possess significant clinical benefits from ICIs compared to those with low TMB. As opposed to bTMB, tTMB was thought more appropriate for stratifying NSCLC patients for ICI treatment.

Optical Phase Array - OPA is a fast, flexible and non-mechanical beam pointing technology, which can be regarded as the extension of microwave phased array to the Optical wave frequency band. It has a wide application prospect and research value in target detection, imaging recognition, tracking scanning, laser interference and other fields. Optical phased array system is composed of a number of array elements, the basic idea is through electric scanning technology and modular design method. The beam can be transmitted, received and detected with high precision by using multiple small aperture beam oriental arrays. Based on acoustic-optic and elector-optic devices, the propagation direction of the beam is changed by controlling the initial phase of each element in the optical aperture, thus completed the laser beam array scan. In this paper, the development background and working principle of optical phased array technology are introduced. Based on the typical application of optical phased array technology, that is, laser phased array radar system, this paper summarizes the research progress and key technology breakthrough of this system in domestic and abroad. Finally, by analyzing the outstanding advantages of optical phased array technology, for one hand the research direction and application prospect of this technology in industrial and military fields are put forward, for the other hand the conceptual design and engineering research of this technology are summarized and prospected.

To evaluate the clinical efficacy and safety of Heyan Kuntai capsule (HYKT) in treating women with infertility caused by diminished ovarian reserve (DOR).One hundred eight eligible patients from three Chinese hospitals were randomly divided into an HYKT treatment group (n = 55) or a dehydroepiandrosterone (DHEA) treatment group (n = 53). Patients in the HYKT group were treated orally with four 0.5 g HYKT three times a day; patients in the DHEA group were treated with one 25.0 mg DHEA capsule three times a day. All patients were treated for 3 months and followed up over a 3-month period.Of 108 patients, 12 dropped out: six from the HYKT group, and six from the DHEA group. Eleven patients got pregnant during the treatment. Serum anti-Müllerian hormone levels and antral follicle counts increased significantly in both groups after treatment (P0.05) especially in the HYKT group (P0.05). Serum follicle stimulating hormone (FSH) levels and FSH/luteinizing hormone ratios decreased (P0.05) with no significant difference between the two groups. Estradiol levels in the HYKT group and DHEA-sulfate levels in the DHEA group both increased (P0.05). The spontaneous pregnancy rates were 12% and 11% in the HYKT and DHEA groups, respectively (not significant). During the follow-up period, 16 patients in the HYKT group underwent in vitro fertilization-embryo transfer (IVF-ET) and the number of retrieved oocytes was (5.1 c1.8). In DHEA group, 20 patients underwent IVF-ET and the number of retrieved oocyte was (4.2 ± 1.9) (not significant); clinical pregnancy rates were 38% in the HYKT group and 20% in DHEA group (not significant). No significant adverse reactions were observed.HYKT can improve the ovarian reserve and hormone levels in patients with infertility caused by DOR. Pregnancy rates after HYKT treatment were similar to those of DHEA treatment. HYKT might be an alternative to the treatment of infertility caused by DOR.

Content-centric networking (CCN) proposes a content-centric paradigm which changes the waist hourglass from Internet protocol (IP) to content chunk. In this paper, based on content chunks, an optimization model of minimizing the total delay time in information centric networking (ICN) is established, and branch-and-bound method and greedy (BG) algorithm is proposed to get the content placement method. As the multipath is natural supported in CCN, chunk-based content placement can decline delay time obviously, even it would increase the calculation amount which can be solved easily by the node's capacity. Simulation results indicate that the chunk-based content placement scheme is better than the single-based cache policy on the network total delay time, and the best number of each content chunk split is decided by the link density and the number of the nodes in the network.

Background: At present, L-DOPA remained the gold standard therapy for motor symptoms of Parkinson’s disease (PD) patients. However, prolonged administration of L-DOPA led to the development of dyskinesia. Aspirin, a non-steroidal anti-inflammatory drug (NSAID), had been widely used to relieve pain and inflammation. Recent studies indicated aspirin produced neuroprotection against dopamine (DA) neuronal loss in animal model. This study aimed to explore the effects of aspirin pre-treatment and co-treatment with L-DOPA on DA neurotoxicity and L-DOPA-induced dyskinesia (LID) as well.Methods: Rats received a single 6-hydroxydopamine (6-OHDA) injection into substantia nigra to induce DA neuronal loss. For aspirin pre-treatment before L-DOPA studies: One day after 6-OHDA stimulation, rats were daily administrated with aspirin for 3 weeks followed by daily L-DOPA treatment along with aspirin for additional 3 weeks. For aspirin co-treatment with L-DOPA studies: Three weeks after 6-OHDA administration, rats were daily treated by L-DOPA together with aspirin for another 3 weeks. DA neurotoxicity was analyzed via rat PD-like behavior test and DA neuronal counting. The movement disorders of dyskinesia triggered by L-DOPA were determined by the abnormal involuntary movements (AIM) scores analysis.Results: we demonstrated both aspirin pre-treatment and co-treatment exerted anti-LID effects during L-DOPA treatment on 6-OHDA-lesioned rats. In addition, aspirin not only ameliorated DA neuronal damage, but also reduced the development of dyskinesia without affecting L-DOPA efficacy. Furtherly, inhibition of glial cells activation and the subsequent neuroinflammatory response might be involved in aspirin-attenuated dyskinesia.Conclusion: the present study suggested aspirin could have beneficial potential to attenuate LID in PD.

The consumers' attention to the basic information on the textile apparel and the purchase channels are surveyed, the relevance between the age, gender, education level, and occupation of the respondents and their attention to the information on the textile apparel, the purchase channels and the product safety indicators are analyzed, and the possibility of injury and the source of accident information under the product's usage scenarios are analyzed, for which the goodness of fit and correlation coefficient are used for analysis and test. The results show that the occupation, education level and age indicate the significant relationship with the purchase channels; the occupation is significantly correlated to the purchase channels; the occupation, education level and age are not significantly associated with the safety indicators of textile apparel.

Automatic joint detection is of vital importance for the teaching of robots before welding and the seam tracking during welding. For narrow butt joints, the traditional structured light method may be ineffective, and many existing detection methods designed for narrow butt joints can only detect their 2D position. However, for butt joints with narrow gaps and 3D trajectories, their 3D position and orientation of the workpiece surface are required. In this paper, a vision based detection method for narrow butt joints is proposed. A crosshair laser is projected onto the workpiece surface and an auxiliary light source is used to illuminate the workpiece surface continuously. Then, images with an appropriate grayscale distribution are grabbed with the auto exposure function of the camera. The 3D position of the joint and the normal vector of the workpiece surface are calculated by the combination of the 2D and 3D information in the images. In addition, the detection method is applied in a robotic seam tracking system for GTAW (gas tungsten arc welding). Different filtering methods are used to smooth the detection results, and compared with the moving average method, the Kalman filter can reduce the dithering of the robot and improve the tracking accuracy significantly.

Laser-induced fluorescence(LIFS), which is one of most effective discrimination methods to identify the material at the molecular level by inducing fluorescence spectrum, has been popularized for its fast and accurate probe’s results. According to the research, violet laser or ultraviolet laser is always used as excitation light source. While, There is no atmospheric window for violet laser and ultraviolet laser, causing laser attenuation along its propagation path. What’s worse, as the laser reaching sample, part of the light is reflected. That is, excitation laser really react on sample to produce fluorescence is very poor, leading to weak fluorescence mingled with the background light collected by LIFS’ processing unit, when it used outdoor. In order to spread LIFS to remote probing under the complex background, study of improving signal-noise ratio for fluorescence channel is a meaningful work. Enhancing the fluorescence intensity and inhibiting background light both can improve fluorescence’ signal-noise ratio. In this article, three different approaches of inhibiting background light are discussed to improve the signal-noise ratio of LIFS. The first method is increasing fluorescence excitation area in the proportion of LIFS’ collecting field by expanding laser beam, if the collecting filed is fixed. The second one is changing field angle base to accommodate laser divergence angle. The third one is setting a very narrow gating circuit to control acquisition circuit, which is shortly open only when fluorescence arriving. At some level, these methods all can reduce the background light. But after discussion, the third one is best with adding gating acquisition circuit to acquisition circuit instead of changing light path, which is effective and economic.

Laser-induced fluorescence system(LIfS) has been found its significant application in identifying one kind of substance from another by its properties even it’s thimbleful, and becomes useful in plenty of fields. Many superior works have reported LIfS’ theoretical analysis , designs and uses. However, the usual LIPS is always constructed in labs to detect matter quite closely, for the system using low-power laser as excitation source and charge coupled device (CCD) as detector. Promoting the detectivity of LIfS is of much concern to spread its application. Here, we take a high-energy narrow-pulse laser instead of commonly used continuous wave laser to operate sample, thus we can get strong fluorescent. Besides, photomultiplier (PMT) with high sensitivity is adopted in our system to detect extremely weak fluorescence after a long flight time from the sample to the detector. Another advantage in our system, as the fluorescence collected into spectroscopy, multiple wavelengths of light can be converted to the corresponding electrical signals with the linear array multichannel PMT. Therefore, at the cost of high-powered incentive and high-sensitive detector, a remote LIFS is get. In order to run this system, it is of importance to turn light signal to digital signal which can be processed by computer. The pulse width of fluorescence is deeply associated with excitation laser, at the nanosecond(ns) level, which has a high demand for acquisition circuit. We design an acquisition circuit including, I/V conversion circuit, amplifying circuit and peak-holding circuit. The simulation of circuit shows that peak-holding circuit can be one effective approach to reducing difficulty of acquisition circuit.

Aiming at the poor applicability, high unproductive energy consumption and the serious wear of the sucker and tube during the application of oil pumping units, screw pumps and electric submersible pumps in low-production and low-permeability wells, directional wells and exceptional wells, a new reciprocating direct-drive electric submersible plunger pump has been developed. For reciprocating direct-drive electric submersible plunger-pump lifting technology, the rotor of submersible linear motor is connected with the plunger of oil-well pump; cable is applied to supply electric energy for the downhole submersible linear motor; and the rotor of motor directly drives the plunger pump to reciprocate and finally realizes the lifting of the produced liquid. For this new-type lifting technology, downhole direct-drive rodless lifting mode is applied, which successfully prevents the wear of the sucker and tube and avoids the unproductive energy consumption that is caused by the movement of sucker rod string when oil pumping units, screw pumps and other rod lifting methods are adopted. Compared to the oil pumping unit with the same displacement, the application of the reciprocating direct-drive electric submersible plunger pump can reduce electric power consumption by more than 40%. Moreover, this new-style reciprocating direct-drive electric submersible plunger pump has no surface movable component, and the well head is sealed. Therefore, it is safe, environmental friendly and easy to maintain.

Stress concentration is a serious threat to the safety of pipeline. It is great significant to security management of oil-gas pipeline that the stress concentration can be tested and evaluated. The relation model between stress and coercive force is established based on hysteresis of ferromagnetic material. Through tensile test, stress damage critical state parameters are obtained, the parameter ranges corresponding with different stress damage state are obtained. Stress damage state is analyzed and evaluated based on these parameters. The results show that the relation between stress and coercive force is linear. The critical parameters of deformation state are corresponded with stress damage critical state parameters. Under three stress damage states: safety, control and danger, the critical coercive force parameter ranges of X80 steel are obtained though experiment. The correctness and the effectiveness of analysis method for stress damage are validated through application on pipeline.

During oil production an acoustic communication mode with downhole oil pipe as channel is one of feasible downhole control method. Based on a mechanism analysis, this paper presents a pipe acoustic transmission mechanism model. The model is derived to obtain a pipe dispersive equation. The simulation of phase velocity, group velocity and dispersion curves of three common oil pipes indicates that spectral distribution of longitudinal wave transmission in pipe presents a comb filter structure, and the passband/stopband distribution approximates periodicity and symmetry on spectrogram. The passband range, stopband range and amplitude value changes with length, cross area, density of oil pipe and joint. And the influence rule is given. Then the optimal frequency is suggested through simulation for downhole wireless communication tools design.

Aiming at the robust attitude control issue on reentry vehicle subject to uncertainties and disturbances. A novel optimal predictive attitude control method integrating with a high order sliding mode observer is proposed in this paper. On the one hand, the proposed optimal one-step predictive control approach can guarantee good dynamic performance of the control system, on the other hand, a high order sliding mode observer is applied to estimating the uncertainties and disturbances exactly, which can strengthen the robustness of the control system. System stability is strictly proved by Lyapunov theory and the domains of convergence are given exactly with/without the observer. Finally, an attitude predictive control law is presented for a reentry vehicle with dynamic characteristic of the actuators. Numerical simulations demonstrate the effectiveness of the proposed control law.

This paper investigates the robust feedback control problem associated with finite time attitude stabilization of a reentry reusable launch vehicle subject to plant uncertainties and external disturbance. An integral terminal sliding mode is proposed firstly to achieve finite time stability in the sliding mode. Then, a robust attitude control for a reentry reusable launch vehicle is derived using the designed integral terminal sliding mode, and the attitude of the reentry reusable launch vehicle can converge to the equilibrium in a finite time with composite actuators. Numerical simulations illustrate the reentry reusable launch vehicle performance obtained under the proposed controller.

A new nonlinear sliding mode controller is presented for a second-order nonlinear dynamic system with mismatch parameter uncertainty and external disturbance. Firstly, this paper proposes a new nonlinear sliding mode with an arctan function on which the system states are stable asymptotically. Secondly, a nonlinear silding mode controller is developed to guarantee that the system states can reach the sliding mode surface from any initial system state in finite time and stay the domain of the equilibrium point. Finally, an illustrative example shows that the controller is robust to parameter uncertainty and eliminate external disturbance caused by chattering nearby the sliding mode surface. Also, consume energy of this method is the least than that of the linear sliding mode controller and terminal sliding mode controller.

There are two main issues, high cost and interrupt response delay for current PACs (programmable automation controllers) which are using high frequency single-chip microprocessors and commercial RTOS (real-time operating system) working by switching the tasks and interrupts. To solve these problems, a new low-cost multi-core heterogeneous PAC structure was proposed. Based on the traditional front-end of interrupt service without interrupt switching delay and the division & deployment of multi real-time tasks. We implemented a new programming language Engineer C including its syntax, compiler and an integrated development environment, which can dynamically divide the multi tasks and deploy the division to single low-cost microcontroller, then built the hardware prototype, which consists of a digital signal board, an analog signal board and a motion control board, every board has its microcontroller and communicates each other by an enhanced SPI bus. Testing results show the hardware prototype and IDE can be provided as a low-cost PAC solution for construction machine. DOI: http://dx.doi.org/10.11591/telkomnika.v11i12.3802

Integration technology of avionics system is a core technology of avionics for all new generation aircrafts. In accordance with the development of integration technology for avionics, this paper describes the composition and structure of avionics system integration technology, analyzes the mechanism and methods of the technology, discusses the abilities and objects of integration technology for avionics system. It also deeply discusses the idea, framework, content, constitution of structural integration, information fusion and mission synthesis of integration for avionics system.

Chassis is one of the key components of tracked test vehicle. The strength and rigidity of chassis must be considered and structure resonance should be avoided during the process of structure design. The stress nephogram and strain nephogram of chassis are obtained, after static analysis in the finite element analysis software ANSYS. The maximum stress is 65.13MPa and the maximum strain is 0.00032mm. They both occur in the place where stiffener of bottom plate and side plate of speed reducer box are welded together. A kind of improved scheme is put forward, considering that the welding allowable stress is smaller than the allowable stress of parent material, and also the stress concentration and residual welding stress exist, though the maximum stress is in the allowed range. Static analysis is made to the improved chassis. The maximum stress becomes 45. 573MPa with 30% reduced, and the maximum strain becomes 0.00022786mm with 28.8% reduced. And the position of maximum stress and maximum strain transfer to the internal corner of crossbeam. And the first six extended natural frequencies of the improved chassis are obtained via modal analysis.

Aiming to the application of Non-monotonic reasoning based on uncertain inference to plan recognition, a new way of knowledge expression model is proposed in mean of extending credibility of TMS node and building evidence transfer mechanism, which ensures the system to inference forward and build hypothesis under the case of the node state is noncommittal. The gene of node reliability and influence degree is introduced to overcome the shortage of only one value of credibility at one time and implement uncertain inference. Theoretical analysis and experimental results demonstrate that our method could describe clearly the process of non-monotonic reasoning based on uncertain inference, so it is expectable for our method to play a useful role in plan recognition system.

There is an increasing performance demand in receiving system of synthetic aperture radar (SAR) in recent days. Different kinds of digital quadrature demodulation (DQD) algorithms have come down to the filter design. A novel DQD filter based on the shifted matched filter is introduced in this paper. The performance of different filters is evaluated based on simulated echo data of one point target. Simulation shows that proposed filter can make the DQD meet precision demand and reduce computation greatly. The work in this paper provides a guide to design digital receiver in SAR.

In radar, sonar and communication applications, and especially in all-digital receivers and software radio systems, baseband in-phase and quadrature (denoted by I and Q) components are usually needed. In a super-heterodyne radar receiver, the conventional method to obtain quadrature components of signals is to multiply the original signal with a complex exponential. In this paper, the fundamental principles of obtain digital quadrature components of the super-heterodyne radar receiver are introduced. Double-IF quadrature demodulation topology is synthesized and fully analyzed in this paper.

Although PCP technology has been used in Daqing Oilfield from 1980s, and the number of PCP wells in the whole oilfield has reached 2429 till September in 2006, it wasn’t applied in polymer flooding producers with displacement of over 150m3/d until 2004. However, the application of the high volume PCP systems has witnessed severe wear issue both in tubing and rods. Study indicated that, due to the great increment in displacement, the original design for smaller volume PCPs showed serious incompatibility with high volume PCP systems. For instance, bigger structure parameter resulted in higher rod oscillation in operation, and pipe string bending issue in high volume PCP was more popular than in lower ones using the traditional anchor. In addition, improper rod guiding also played an important role in wear of tubing and rod string. This paper analyzes the mechanism of tubing & rod wear for high volume PCPs in detail, and presents a series of harness treatments including: 1) optimizing pump selection method and operation parameter; 2) improving tubing anchoring method; and 3) optimizing rod string guiding method. Based on the above treatments, a set of optimum design model for high volume PCPs was created. Experiments and application showed that, using this optimum design model, tubing & rod wear failure rate was decreased sharply, and the operation performance was improved effectively for high volume PCPs in polymer flooding area. This study contributed a lot in not only improving the design method of traditional PCP technology, expanding the application scale of PCP system, but also presenting a good reference on how to squeeze the benefit of artificial lift technology in EOR stage.

To solve the problems of network bandwidth bottleneck and insufficient service ability of networked manufacturing application service provider platform, a grid-based more-for-more service model was put forward on the basis of the present one-for-more model which adopts the central server. And the application service of manufacturing resource offered by the platform was executed cooperatively among more than one grid service nodes. A service-oriented classification model of manufacturing resource based on ASP platform more-for-more model was established. And the RDF-based metadata specification language was realized to enhance the ability of interoperability and access. In the aspect of manufacturing resource organization and discovery, the incorporation of distributed and centralized mechanism was adopted. Different types of manufacturing resource were managed by the corresponding ASP nodes, and these self-governed ASP nodes had constructed the grid-based network topology. Furthermore, the algorithm as well as performance evaluating of resource discovery was described. Finally, the implementation technologies of the platform were introduced, and feasibility and practicability of the proposed model were verified by the development and preliminary application.

Publisher Summary This chapter reflects fault tolerance in certain military applications, in atomic power plants, or on aircraft and introduces some ideas on how to apply evolution to existing fault tolerance schemes. Because of Field Programmable Gate Arrays (FPGAs) inherent time to-market, low NRE, and flexibility advantages over application-specific integrated circuits (ASICs) their popularity continues to grow in many applications, including space, military, and avionics. The extensive use of FPGAs in these applications underscores the importance of understanding the different effects on FPGAs of ionizing radiation components, such as neutrons, protons, and heavy ions. The chapter examines the cause and effects of Single Event Upset (SEU) and the SEU susceptibility. It also examines SEU mitigation techniques and discusses the susceptibility of static random access memories (SRAM) based FPGAs to SEUs. The chapter describes the ways of increasing the circuit's reliability with the help of evolutionary techniques, proposes the use of evolvable hardware (EHW) in the Triple Modular Redundancy (TMR) fault tolerant circuit design to achieve Evolutionary Fault Repair TMR fault-tolerance circuit, and illustrates the immunity of FPGA devices to SEU effects.

A magnetron arc evaporation ion plating(MAEIP) system has been constructed using disk titanium cathode Ti-N thin film with gold-like colour has been prepared using MAEIP techniques. The reflectances of Ti-N thin films in the wavelength range 350-2500 nm has been measured at near normal incidence by UV-365 spectrophotometer. X-ray diffraction analysis shows that the magnetron arc evaporation ion plated Ti-N thin films are polycrystalline TiN. The TiN thin films as decorative and hard coatings have been widely used in the watch-covers, watch-chains, Badding iron balls and tools, etc.