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In this study, the enhanced surface properties and microstructure evolution of quenched and tempered cold work die steel Cr12MoV, which were induced by ultrasonic surface rolling process combined with deep cryogenic treatment (UDCT), were systematically investigated. The results indicated that UDCT had an advantage over conventional ultrasonic surface rolling process (USRP) in improving surface mechanical properties, including smaller surface roughness and smoother machined surface with less cracks and defects; higher surface microindentation hardness with the value of ~ 890 HV (increased by ~ 6.2% compared with USRP); and lower friction coefficient. Such enhancements in surface properties are mainly attributed to the martensitic transformation of retained austenite, the dispersion strengthening of small secondary carbides and the homogenized carbides distribution during UDCT.

A feasible design of ultra-dense Small cell network involves an effective solution to the interference coordination especially in cell edge. In this paper, we propose a channel state and interference aware power allocation scheme (PAG) as an enhanced solution to improve the system performance, especially for the cell-edge users. Cournot model in Non-cooperative game is employed for power adjustment in Small cell clusters to increase cell-edge users' throughput by considering the power limitation and interference coordination. Additionally, we take iterative Water Filling scheme as a comparison to clarify that the PAG scheme has struck a favorable balance between system efficiency and fairness. Simulation results show that the proposed scheme contributes to the enhancement of edge users' throughput and cells' coverage. Moreover, the scheme is observed to show a stronger adaptability in denser Small cell networks.

A simple and safe triangle-valve technique (TVT) was applied in proximal gastrectomy (PG) in order to prevent postoperative gastric reflux among patients with adenocarcinoma of the esophagogastric junction (AEG). The clinical outcomes were evaluated in comparison to those of canonical total gastrectomy (TG). This retrospective study of 74 AEG patients compared two surgical procedures, PG-TVT (n=44) and TG (n=30), in terms of surgical outcomes, postoperative complications and nutritional status. The Reflux Disease Questionnaire (RDQ) was used to evaluate reflux esophagitis, and patients with an RDQ score of ≥12 points were diagnosed with gastroesophageal reflux disease (GERD). The mean operative time was significantly shorter in the PG-TVT group (242.6 min) compared with that in the TG group (288.1 min). The overall postoperative complication rate did not differ significantly between the PG-TVT and TG groups. All the patients were followed up for 6 months, and none developed cancer recurrence in distant organs, gastric remnant, or lymph nodes. The GERD incidence was similar between the PG-TVT and TG groups. The mean levels of total protein and albumin within 6 months were significantly higher in the PG-TVT group compared with those in the TG group after adjustingtthe time effect and the interaction of time and surgical methods. The level of total protein significantly increased within 6 months in the PG-TVT group, but decreased in the TG group. Therefore, PG-TVT has several advantages over TG for patients with AEG, including a shorter operative time and better postoperative nutritional status, whereas the incidence of GERD was found to be similar between the two techniques.

This article is mainly focused on a method for stabilizing the position of an incident laser beam position by using a closed-loop fast steering mirror system. According to the input and output data, a model for the fast steering mirror system is established, which is utilized for the closed-loop controller. In the experiment, the spot centroid position, which is obtained by means of a position sensitive detector, is used as a signal for modeling and closed loop control. Because of the difference between the levels of atmospheric turbulence over water and over rock, the effects of the fast steering mirror system for the two cases may also differ. Therefore, experiments of laser beam stabilization have been carried out in these two different environments. The results show that the spot jitter is stronger when the laser is transmitted over rock, compared to transmission over water, and that spot jitter below 25 Hz can be restricted by closed-loop control in both environments.

Based on the principle of phase laser ranging, the idea of using phase laser range finder for underwater ranging was proposed, and the feasibility of underwater phase laser ranging was analyzed in principle. Through the underwater distance measurement experiments, the feasibility of underwater phase laser ranging was verified, the range calibration algorithm for underwater phase laser range finder was completed, and the effects of water turbidity on the dynamic range and distance measurement accuracy of laser ranging were explored. The experimental results show that the average ranging error of underwater laser range finder after calibration is not more than 3 mm in the range of 3.5 m, and there is an exponential decay relationship between range and water turbidity. The underwater phase laser range finder provides a new method for the detection of underwater distance, which can achieve accurate ranging at short range of underwater target.

Progressive addition lens (PAL) is currently the state-of-the-art in multifocal correction visual for freeform lens. The PAL is used to correct presbyopia by the distributing optical powers of the three zones, which are far zone, near zone and intermediate zone. As the dioptre of progressive zone varies continuously, the lenses realize simultaneously far view and near view by a pair of glasses. Because the PAL is a freeform surface with a variable radius of curvature, complex shape, processing difficulties, low efficiency, big fluctuation of interpolation error and so on. In this paper, the design surface is discretized by the constant angle method and compensates the path of the diamond tool nose radius with AKIMA interpolation method, which can identify the machine tool of the tool locus, and exploitable fast tool servo technology controls the diamond tools movement and path. MATLAB simulation results show that this method is generally more approximate to the ideal trajectory, which is not only to ensure that surface profile accuracy, but also meet the requirements of the processing efficiency and better control the surface profile.

Magnetorheological finishing (MRF) is a key polishing technique capable of rapidly converging to the required surface figure. Due to the deficiency of general one-polishing-head MRF technology, a dual polishing heads MRF technology was studied and a dual polishing heads MRF machine with 8 axes was developed. The machine has the ability to manufacture large aperture optics with high figure accuracy. The large polishing head is suitable for polishing large aperture optics, controlling large spatial length’s wave structures, correcting low-medium frequency errors with high removal rates. While the small polishing head has more advantages in manufacturing small aperture optics, controlling small spatial wavelength’s wave structures, correcting mid-high frequency and removing nanoscale materials. Material removal characteristic and figure correction ability for each of large and small polishing head was studied. Each of two polishing heads respectively acquired stable and valid polishing removal function and ultra-precision flat sample. After a single polishing iteration using small polishing head, the figure error in 45mm diameter of a 50 mm diameter plano optics was significantly improved from 0.21λ to 0.08λ by PV (RMS 0.053λ to 0.015λ). After three polishing iterations using large polishing head , the figure error in 410mm×410mm of a 430mm×430mm large plano optics was significantly improved from 0.40λ to 0.10λ by PV (RMS 0.068λ to 0.013λ) .This results show that the dual polishing heads MRF machine not only have good material removal stability, but also excellent figure correction capability.

A TCP flow increases its sending rate linearity until a packet loss is detected. The lost packets can be seen as the cost paid by the method of probing available network bandwidth. A router can decide whether to drop a received data packet only based on its locally available network resource without considering the sender of the packet is responsible or not. Therefore, such a scheme does not motivate end users to use congestion control mechanism. Accordingly, TCP flows have to endure packet loss. In this paper, we propose a novel congestion control mechanism named as probe follow congestion control (PF-CC) mechanism, with which users can be classified into two categories: probers and followers. Probers are those users that are responsible for probing available network resources. Followers are those users that regulate their behavior based on the probing results by probers. Thus, a follower has a small probability of packet loss since there is no available network resource. The routers drop a packet by considering the behavior of its source. More specifically, as an example, a router can reward those responsible users by rarely dropping their packet and punish those irresponsible users by dropping their packets severely. Therefore, the PF-CC mechanism can motivate end-users to conduct end-to-end congestion control. Specifications of the mechanism are presented and also its performance is evaluated using extensive simulations and analysis.