A New Computed Torque Control System with an Uncertain RBF Neural Network Controller for a 7-DOF Robot

A novel percutaneous puncture robot system is proposed in the paper. Increasing the surgical equipment precision to reduce the patient\u27s pain and the doctor\u27s operation difficulty to treat smaller tumors can increase the success rate of surgery. To attain this goal, an optimized Computed Torque Law (CTL) using a radial basis function (RBF) neural network controller (RCTL) is proposed to improve the direction and position accuracy. BRF neural network with an uncertain term (URBF) which is able to compensate the system error caused by the imprecision of the model is added in the RCTL system. At first, a 7-DOF robotic system is established. It consists of robotic arm and actuator control channels. Now, the RBF compensator is added to the CTL to adjust the robot arm to reduce the position and direction errors. The angle and velocity errors of the robot arm are compensated using the RBF controller. According to the Lyapunov theory, the accuracy of torque control system depends on path tracking errors, inertia of robot, dynamic parameters and disturbance of each joint. Compared to general CTL approaches, the precision of a 7-DOF robot could be improved by adjusting the RBF parameters

Planning analysis for locally advanced lung cancer: dosimetric and efficiency comparisons between intensity-modulated radiotherapy (IMRT), single-arc/partial-arc volumetric modulated arc therapy (SA/PA-VMAT)

<p>Abstract</p> <p>Purpose</p> <p>To analyze the differences between the intensity-modulated radiotherapy (IMRT), single/partial-arc volumetric modulated arc therapy (SA/PA-VMAT) techniques in treatment planning for locally advanced lung cancer.</p> <p>Materials and methods</p> <p>12 patients were retrospectively studied. In each patient's case, several parameters were analyzed based on the dose-volume histograms (DVH) of the IMRT, SA/PA-VMAT plans respectively. Also, each plan was delivered to a phantom for time comparison.</p> <p>Results</p> <p>The SA-VMAT plans showed the superior target dose coverage, although the minimum/mean/maximum doses to the target were similar. For the total and contralateral lungs, the higher V_5/10, lower V_20/30and mean lung dose (MLD) were observed in the SA/PA-VMAT plans (<it>p </it>< 0.05, respectively). The PA-VMAT technique improves the dose sparing (V₂₀, V₃₀and MLD) of the controlateral lung more notably, comparing to those parameters of the IMRT and SA-VMAT plans respectively. The delivered monitor units (MUs) and treatment times were reduced significantly with VMAT plans, especially PA-VMAT plans (for MUs: mean 458.3 <it>vs</it>. 439.2 <it>vs</it>. 435.7 MUs, <it>p </it>< 0.05 and for treatment time: mean 13.7 <it>vs</it>. 10.6 <it>vs</it>. 6.4 minutes, <it>p </it>< 0.01).</p> <p>Conclusions</p> <p>The SA-VMAT technique achieves highly conformal dose distribution to the target. Comparing to the IMRT plans, the higher V_5/10, lower V_20/30and MLD were observed in the total and contralateral lungs in the VMAT plans, especially in the PA-VMAT plans. The SA/PA-VMAT plans also reduced treatment time with more efficient dose delivering. But the clinical benefit of the VMAT technique for locally advanced lung cancer needs further investigations.</p

Evaluation of instantaneous and cumulative models for reactivity ratio estimation with multiresponse scenarios

Estimating reactivity ratios in multicomponent polymerizations is becoming increasingly important. At the same time, using cumulative models is becoming imperative, as some multicomponent systems are inherently so fast that instantaneous "approximate" models can not be used. In the first part of the thesis, triad fractions (sequence length characteristics) are employed in a multiresponse scenario, investigating different error structures and levels. A comparison is given between instantaneous triad fraction models and instantaneous composition model, which represent the current state-of-the-art. In the second part of the thesis, extensions are discussed with cumulative composition and triad fraction models over the whole conversion range, thus relating the problem of reactivity ratio estimation to the optimal design of experiments (i. e. optimal sampling) over polymerization time and conversion. The performance of cumulative multiresponse models is superior to that of their instantaneous counterparts, which can be explained from an information content point of view. As a side-project, the existence of azeotropic points is investigated in terpolymer (Alfrey-Goldfinger equation) and tetrapolymer (Walling-Briggs equation) systems

Effects of wave-current interaction on storm surge in the Taiwan Strait: Insights from Typhoon Morakot

The effects of wave-current interaction on storm surge are investigated by a two-dimensional wave-current coupling model through simulations of Typhoon Morakot in the Taiwan Strait. The results show that wind wave and slope of sea floor govern wave setup modulations within the nearshore surf zone. Wave setup during Morakot can contribute up to 24% of the total storm surge with a maximum value of 0.28 m. The large wave setup commonly coincides with enhanced radiation stress gradient, which is itself associated with transfer of wave momentum flux. Water levels are to leading order in modulating significant wave height inside the estuary. High water levels due to tidal change and storm surge stabilize the wind wave and decay wave breaking. Outside of the estuary, waves are mainly affected by the current-induced modification of wind energy input to the wave generation. By comparing the observed significant wave height and water level with the results from uncoupled and coupled simulations, the latter shows a better agreement with the observations. It suggests that wave-current interaction plays an important role in determining the extreme storm surge and wave height in the study area and should not be neglected in a typhoon forecast

Women artists of the late 19th century: continuity and change at the sunset of imperial China

Increasing attention to the history of Chinese women artists gives further impetus to re-evaluation of their artistic contribution. Here I focus on developments in women’s art in the later part of the 19th century, entering into an interrogation of the assumption that the century had witnessed its decline in tandem with the decline of the Imperial China itself. A focus of the article is the 2017 Zhejiang exhibition, which has served to further intensify the imperative for research. Adopting a perspective based on gender and class, this paper examines the work of the female Chinese artists of the late 19th century both in the traditional Jiangnan area, which had been the epicentre of culture and economy, and in the newly developing trade areas, most notably Shanghai. There a vibrant art market emerged, bringing significant opportunities for women artists from broader social strata. This dynamic is illustrated by the particular example of Ren Xia. In these circumstances significant changes took place in the context of the presence of continuity in women’s aesthetic production, while a traditional male discourse remained hegemonic

Women artists of the late 19th century: continuity and change at the sunset of imperial China

Increasing attention to the history of Chinese women artists gives further impetus to re-evaluation of their artistic contribution. Here I focus on developments in women’s art in the later part of the 19th century, entering into an interrogation of the assumption that the century had witnessed its decline in tandem with the decline of the Imperial China itself. A focus of the article is the 2017 Zhejiang exhibition, which has served to further intensify the imperative for research. Adopting a perspective based on gender and class, this paper examines the work of the female Chinese artists of the late 19th century both in the traditional Jiangnan area, which had been the epicentre of culture and economy, and in the newly developing trade areas, most notably Shanghai. There a vibrant art market emerged, bringing significant opportunities for women artists from broader social strata. This dynamic is illustrated by the particular example of Ren Xia. In these circumstances significant changes took place in the context of the presence of continuity in women’s aesthetic production, while a traditional male discourse remained hegemonic

Issues and challenges of reclaimed water usage: A case study of the Dragon-shaped River in the Beijing Olympic Park

Increased use of reclaimed water could be one of the solutions to Beijing’s growing water shortage, particularly for non-potable (e.g. landscaping) purposes. The ‘Dragon-shaped River’, a large artificial waterscape built on the site of the 2008 Beijing Olympic games, offers a useful case study of the issues and challenges attendant on wastewater reclamation and reuse. Of particular interest is the use of phytoremediation techniques for bioremediation of nutrient loads. This paper presents the results of ongoing monitoring which indicates that phytoremediation is succeeding in preventing eutrophication, though some challenges, notably management of aquatic biomass, remain

Phase separation and enhanced wear resistance of Cu88Fe12 immiscible coating prepared by laser cladding

In order to eliminate the microstructure segregation of Cu–Fe immiscible alloys which characterized with a liquid miscible gap, the Cu88Fe12 (wt.%) immiscible coating was prepared by laser cladding. The phase separation characteristic and wear resistance of the Cu88Fe12 (wt.%) immiscible coating were also investigated. The results show that the size of the milled Cu88Fe12 composite powder is reduced comparing to that of the un-milled powder due to fracturing during mechanical milling. Moreover, the demixing or delamination disappears in the Cu88Fe12 immiscible coating and a large amount of face-centered-cubic (fcc) γ-Fe and body-centered-cubic (bcc) α-Fe particles are dispersed in the face-centered-cubic (fcc) ɛ-Cu matrix as a result of liquid phase separation. The size of Fe-rich particles presents an increasing tendency from the bottom to the top of the immiscible coating. As a result, the microhardness of the immiscible coating is improved compared with brass (∼138 HV0.2) due to the presence of high-hardness Fe-rich particles (∼191 HV0.2) and the solid solution strengthening effect of Fe in Cu-rich matrix. Furthermore, the width of ploughing, the width and height of wear scar on the surface of the immiscible coating are much less than those on the surface of brass. Therefore, the wear resistance of the immiscible coating is remarkably enhanced compared with brass

Zhuang handicraft in the Baise area: The gendered cultural significance of Mo-Mie

This research is of interest at local, Chinese national, and global levels. Locally, I examine the cultural production of the Zhuang people around Baise in the Guangxi Zhuang Autonomous Region, the Zhuang being one of the 56 official nationalities in China. Globally, there is increasing interest in China and its make-up, including the specific national cultural components. I attempt to contribute to clarity in attaching aesthetic and social value to cultural production that is often carried out by women and largely categorised as ‘craft’, rather than ‘art’. I adopt an empirical approach by engaging with the producers of such work and examine their relationship to the processes of its consumption. I found that the traditional family handcraft of Mo-Mie had been largely forgotten until coming back into focus in 2009 due to government efforts to explore China's national cultures. This short piece of research cannot ‘solve’ the problems that face the history of art. My attempt, in a limited way, is continue the process of examination and appreciation of unique forms of cultural production that exist, in order that we might begin to develop wider conclusions about the place of such creativity in appreciation of human heritage