作者机构：
[Chen, Haifei] Cent South Univ Forestry & Technol, Sch Mech & Elect Engn, Changsha 410000, Peoples R China.;[Xu, Yong] Beijing Inst Technol, Sch Automat, Beijing 100081, Peoples R China.
通讯机构：
[Haifei Chen] S;School of Mechanical and Electrical Engineering, Central South University of Forestry and Technology, Changsha 410000, China
关键词：
Relay communication based space;teleoperation;Direct recursion generalized predictive control;Dual regression Pseudo-PF feedback
摘要：
This paper studies the high telepresence control for the relay communication based space teleoperation. High telepresence requires real-time, accurate force perception and good position tracking, but all of them are destroyed or affected by time delay. To eliminate the influence of time delay, direct recursive generalized predictive control (DR-GPC) is quoted into this paper to realize position tracking. As for the other two properties, the pseudo position-force (Pseudo-PF) feedback strategy (composed of parameter identification and force reconstruction) is a good way as it can provide real-time and precise force feedback when environment change slowly and time delay is relatively small. However, complex and changeable environment and serious and complex time delay in space teleoperation make the environment force parameter available to force reconstruction is outdated and cannot realize accurate force rebuilding. To solve this problem, we propose a dual regression Pseudo-PF feedback strategy. Compared with the traditional one, its biggest change is the introduction of dual regression that consists of time delay prediction and parameter regression. The former predicts time delay and provides it to the latter to determine the forward prediction steps, while the latter regresses the actual latest and precise environment force parameter according to the forward prediction steps. With the cooperation of time delay prediction and parameter regression, the influence of fast changing environment or serious and complex time delay on force reconstruction can be effectively overcome, so as to realize real-time and accurate force feedback. Finally, DR-GPC and dual regression Pseudo-PF feedback strategies cooperate to achieve high telepresence control, and simulation is given to show its effectiveness.
作者机构：
[Yudi Zhao] College of Information Science& Electronic Engineering, Hunan City University , Yiyang, Hunan, 413000, China;[Zhizhe Yu] School of International Education, Wuhan University of Technology , Hubei, Wuhan, 430070, China;[Yunpeng Zhu] School of Chang’an Dublin International College of Transportation at Chang’an University, Chang’an University Xi’an , ShaanXi, 710064, China;[Shuai Wang] College of Mechanical and Electrical Engineering, Central South University of Forestry and Technology , Changsha, Hunan, 410000, China
通讯机构：
[Shuai Wang] C;College of Mechanical and Electrical Engineering, Central South University of Forestry and Technology , Changsha, Hunan, 410000, China
摘要：
Endoscopy is one of the cornerstones in the field of gastroenterology. The growth of image technology in recent years has given technological support for the expertise of the medical device sector, particularly in the area of medical imaging. Computer vision uses real-time Localization and Mapping Create SLAM (simultaneous localization and mapping). The purpose of SLAM technology is to map the location environment, and at the same time use the signal provided by the sensors to locate the sensor system in the environment. In order to simplify the navigation system for minimally invasive abdominal surgery, a laparoscopic navigation system based on SLAM was developed. Combining medical information with real-time laparoscopic video can increase the doctor’s field of view, assist in identifying critical areas, and enable safer and more effective surgical procedures. The purpose of this paper is to study how SLAM technology can solve some problems in minimally invasive surgery in medical endoscopy and to look forward to the bright future of SLAM technology and medical endoscopy.
期刊：
Journal of Colloid and Interface Science,2023年646:67-77 ISSN：0021-9797
通讯作者：
Li, LQ;Su, RK
作者机构：
[Ma, Xiancheng; Qi, Tingting] Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410004, Hunan, Peoples R China.;[Li, Liqing; Li, LQ; Zeng, Zheng] Cent South Univ, Sch Energy Sci & Engn, Changsha 410083, Hunan, Peoples R China.;[Su, Rongkui; Su, RK] Cent South Univ Forestry & Technol, Coll Environm Sci & Engn, Changsha 410083, Hunan, Peoples R China.;[Chen, Ruofei] Zhongkai Univ Agr & Engn, Sch Electromech Engn, Guangzhou 510225, Guangdong, Peoples R China.;[Wang, Shaobin] Univ Adelaide, Sch Chem Engn & Adv Mat, 108 King William St, Adelaide, SA 5005, Australia.
通讯机构：
[Li, LQ ; Su, RK ] C;Cent South Univ, Sch Energy Sci & Engn, Changsha 410083, Hunan, Peoples R China.;Cent South Univ Forestry & Technol, Coll Environm Sci & Engn, Changsha 410083, Hunan, Peoples R China.
关键词：
Acetone adsorption;Grand canonical Monte Carlo;Oxygen groups;Pore sizes;Porous carbon
摘要：
The influence of different pore size and oxygen groups for porous carbons on acetone adsorption at different pressure was studied by using experimental data and theoretical calculation, and the results were applied to prepare carbon-based adsorbents with superior adsorption capacity. First, we successfully prepared five types of porous carbons with different gradient pore structure but similar oxygen contents (4.9±0.25 at.%). We found that the acetone uptake at different pressure depends on the different pore sizes. Besides, we demonstrate how to accurately decompose the acetone adsorption isotherm into multiple sub-isotherms based on different pore sizes. Based on the isotherm decomposition method, the acetone adsorption at 18kPa is mainly in the form of pore-filling adsorption in the pore size range of 0.6-2.0nm. When the pore size is greater than 2nm, the acetone uptake mainly depends on the surface area. Second, porous carbons with different oxygen content, similar surface area and pore structure were prepared to study the influence of oxygen groups on acetone adsorption. The results show that the acetone adsorption capacity is determined by the pore structure at relatively high pressure, and the oxygen groups only slightly increase the adsorption capacity. However, the oxygen groups can provide more active sites, thereby enhancing acetone adsorption at low pressure.
期刊：
Chemical Engineering Journal,2023年471:144517 ISSN：1385-8947
通讯作者：
Li, LQ;Su, RK
作者机构：
[Ma, Xiancheng] Cent South Univ Forestry & Technol, Coll Mech & Elect Engn, Changsha 410083, Hunan, Peoples R China.;[Li, Liqing; Li, LQ; Zeng, Zheng] Cent South Univ, Sch Energy Sci & Engn, Changsha 410083, Hunan, Peoples R China.;[Su, Rongkui; Wang, Hanqing; Su, RK] Cent South Univ Forestry & Technol, Coll Environm Sci & Engn, Changsha 410083, Hunan, Peoples R China.;[Wang, Shaobin] Univ Adelaide, Sch Chem Engn & Adv Mat, Adelaide, SA 5005, Australia.
通讯机构：
[Li, LQ ; Su, RK ] C;Cent South Univ, Sch Energy Sci & Engn, Changsha 410083, Hunan, Peoples R China.;Cent South Univ Forestry & Technol, Coll Environm Sci & Engn, Changsha 410083, Hunan, Peoples R China.
关键词：
Wood-based evaporator;Interfacial water evaporation;Solar energy;Structural design
摘要：
Solar water evaporation plays an important role in the production of low-energy freshwater, which is essential for economic development and human health. The use of solar powered green water evaporation technology has attracted more and more attention as a sustainable solution to water shortage and environmental governance. Among photothermal materials, wood-based photothermal evaporators have attracted researchers' interest because of their abundance, low cost, biodegradability, low thermal conductivity, hydrophilicity and natural capillary mechanism. In this review, we first summarized the advantages of wood-based solar evaporators, including pore structure and chemical structure. Secondly, the latest progress of wood-based solar evaporators is summarized from the aspects of photothermal material decorative wood, carbonized wood, structural design, etc., and the recent progress in the application of wood evaporators in seawater desalination, wastewater purification and energy production were discussed. Finally, the scientific and technical challenges facing the application of wood-based solar evaporators, and future research directions in this field are outlined.
摘要：
The characteristic substances in citrus volatile organic compounds (VOCs) are associated with the infestation of the Bactrocera dorsalis (Hendel), which provides a noninvasive evaluation method to discriminate infested citrus. This paper developed an olfactory detection system based on a quartz crystal microbalance (QCM) sensor array and classification algorithms to identify the citrus infested with B. dorsalis. Six characteristic substances, including D-limonene, myrcene, alpha-pinene, decanal, linalool, and beta-ocimene, which vary significantly after B. dorsalis infestation were selected as template molecules to prepare molecularly imprinted polymers (MIPs) and modify QCM respectively. The experimental results show that the prepared MIPs-QCM sensors had sensitivity in the range of 0.043-0.070 Hz/(mg/m3), and their stability and reproducibility were above 93.1%. Four sensors that contributed to the classification were screened by a stepwise discriminant analysis. Afterward, Bayesian optimization was employed to optimize the hyperparameters. The accuracy of the optimized support vector machine (SVM) reached 94.17%. The olfactory detection system developed in this study enables the discrimi-nation of citrus infested with B. dorsalis, which may have potential applications in the field of post-harvest treatment of citrus.
摘要：
Using functional phosphors that have a range of benefits, such as quick response to n-UV/blue light excitation, high quantum efficiency and low thermal quenching is crucial. In this work, we have utilized the traditional high-temperature solid-state reaction to synthesized Ce3+, Tb3+ single- and co-doped KBaBP2O8 (KBBPO) phosphors. The phase purity, crystal structure, surface morphology, decay behavior, thermal stability, the luminescence properties and energy transfer process from Ce3+ to Tb3+ were investigated in details. Due to the Ce3+ can adequately sensitize Tb3+, the co-doped phosphors can be effectively excited by near-ultraviolet (NUV) light. The emission color chromaticity for the various KBBPO phosphors varies from dark blue to bright green with the increased concentration of Tb3+. The energy transfer mechanism between Ce3+ and Tb3+ is dominated by the exchange interaction, while the efficiency of the energy transfer is calculated as 59.29%. The optimal KBaBP2O8: 0.02Ce3+, 0.05 Tb3+ phosphor demonstrated low thermal quenching, which only reduces 19.3% of the initial intensity at 150 degrees C. The new KBaBP2O8: Ce3+, Tb3+ phosphor will be a potential candidate for widecolor-gamut display backlights.
作者机构：
[Wen, Tao; Li, Dapeng; Long, Jiang; Gong, Zhongliang; Tang, Ziye; Wen, T; Han, Longbo] Cent South Univ Forestry & Technol, Sch Mech & Elect Engn, Changsha 410004, Peoples R China.;[Wen, Liang] South China Normal Univ, Coll Life Sci, Guangzhou 510630, Peoples R China.;[Peng, Hailong] Nanchang Univ, Dept Chem & Pharmaceut Engn, Nanchang 330031, Peoples R China.
通讯机构：
[Wen, T ] C;Cent South Univ Forestry & Technol, Sch Mech & Elect Engn, Changsha 410004, Peoples R China.
关键词：
multi-path spectra;citrus infestation;transmittance;Bactrocera dorsalis (Hendel);partial least squares;classification
摘要：
In this study, a multi-path Vis/NIR spectroscopy system was developed to detect the presence of Bactrocera dorsalis (Hendel) infestations of citrus fruit. Spectra were acquired for 252 citrus fruit, 126 of which were infested. Two hundred and fifty-two spectra were acquired for modeling in their un-infested stage, slightly infested stage, and seriously infested stage. The location of the infestation is unclear, and considering the impact of the light path on the location of the infestation, each citrus fruit was tested in three orientations (i.e., fruit stalks facing upward (A), fruit stalks facing horizontally (B), and fruit stalks facing downward (C)). Classification models based on joint X-Y distance, multiple transmittance calibration, competitive adaptive reweighted sampling, and partial least squares discriminant analysis (SPXY-MSC-CARS-PLS-DA) were developed on the spectra of each light path, and the average spectra of the four light paths was calculated, to compare their performance in infestation classification. The results show the classification result changed with the light path and fruit orientation. The average spectra for each fruit orientation consistently gave better classification results, with overall accuracies of 92.9%, 89.3%, and 90.5% for orientations A, B, and C, respectively. Moreover, the best model had a Kappa value of 0.89, and gave 95.2%, 80.1%, and 100.0% accuracy for un-infested, slightly infested, and seriously infested citrus fruit. Furthermore, the classification results for infested citrus fruits were better when using the average spectra than using the spectrum of each single light path. Therefore, the multi-path Vis/NIR spectroscopy system is conducive to the detection of B. dorsalis infestation in citrus fruits.
摘要：
The scientific design and preparation of porous carbon with high VOCs (such as acetone) adsorption capacity are crucial for waste gas treatment. However, it is still challenging to explain the microscopic mechanism of acetone uptake on porous carbon because of the different adsorption conditions, as well as various chemical properties and different pore structures of porous carbon. Here, the prediction model of the adsorption conditions, nitrogen/oxygen groups and pore structures on acetone adsorption capacity was established by machine learning, and the contribution of the nitrogen/oxygen groups and pore structures of porous carbons to the acetone adsorption capacity at different adsorption pressures was discussed. The results display that the nitrogen/oxygen groups and micropore volume are the main factors affecting the adsorption capacity of acetone at relatively low pressure, while the adsorption capacity at relatively high pressure is determined by total pore volume. Subsequently, three kinds of porous carbon with different oxygen content and gradient pore size distribution were synthesized, and acetone adsorption isotherms were tested. The effects of chemical properties and pore structure on acetone adsorption at different pressure were studied, and the results were consistent with those of machine learning. However, the results are challenging to illustrate the effect of single pore size and functional group type on acetone adsorption performance. Finally, molecular simulation was used to calculate acetone adsorption isotherms with various nitrogen/oxygen groups and different pore sizes, further revealing the adsorption mechanism of acetone with nitrogen/oxygen groups and pore size. Based on machine learning and molecular simulation results, new insights into the adsorption behavior of acetone were revealed, providing theoretical support for the sustainable development of carbon-based adsorbents for acetone waste gas treatment.
摘要：
利用飞秒激光相位掩模加工方法制造光纤布拉格光栅（FBG），并研究了激光能量和曝光时间对FBG波长、反射率和带宽的影响规律。研究发现，随着曝光时间的增加，光纤的折射率调制量逐渐变大，耦合效率增大，反射率逐渐变大。当光纤耦合效率达到饱和时，反射率保持不变；当过曝光时，反射率轻微减小，光纤的平均有效折射率和折射率调制深度均变大，带宽增大。随着激光能量的增大，达到最大反射率所需要的曝光时间缩短，且FBG波长的红移量越多，带宽就越大。过大的激光能量会使平均有效折射率和折射率调制深度变大，从而导致FBG主谐振峰两边的旁瓣增多，影响光谱质量。另外，短波方向旁瓣的振荡比较显著，而长波方向则比较平顺。因此，在实际加工中需要选择合适的激光曝光能量和曝光时间。实验获得的最大FBG反射强度达到15 dB，且其光谱变化和理论分析一致。该研究为高质量FBG的制造和光谱特性优化提供了实验依据。 The influence of laser energy on the FBG reflection spectrum is as follows. As shown in Fig. 3(a), the higher the laser energy, the greater the red shift of the wavelength at the same exposure time. The corresponding wavelength at the exposure time of 125 s is 1549.61 nm and 1549.75 nm for the laser energy of 700 mW and 800 mW, respectively. The higher the laser energy, the higher is the reflectivity; however, the bandwidth also increases significantly. The corresponding maximum reflectivity values of FBG under the two conditions are 14.3 dB and 15 dB, respectively, as shown in Fig. 3(b). Simultaneously, the corresponding bandwidths of approximately 0.62 nm and 0.74 nm are achieved, as shown in Fig. 3(c). In addition, a higher laser energy leads to more side lobes on both sides of the main resonant peak in the spectrum, as shown in Fig.4. Objective Fiber Bragg gratings (FBGs) exhibit the advantages of small size, reflection operation, high sensitivity, and wavelength encoding. Further, the FBGs induced by femtosecond laser pulses have unique advantages, such as high-temperature resistance and high-temperature stability, which are particularly suitable for sensing applications under extreme operating conditions, and thus, these FBGs have been widely used in aerospace and other fields. Fabricating FBGs via phase mask technology has the merits of effective processing and high device consistency and has been demonstrated to be the most promising industrial technology scheme. However, limited research has been conducted on the spectral characteristics of FBGs. We fabricate FBGs via the femtosecond laser phase mask method and extensively study the influence of laser energy and exposure time on the wavelength, reflectivity, and bandwidth of the FBGs. The factors influencing the FBG spectrum are theoretically and experimentally analyzed. This study offers an experimental basis and guidance for the fabrication of high-quality FBG devices using femtosecond laser technology. Methods In this study, FBGs fabricated via the femtosecond laser phase mask method are experimentally demonstrated. The light path of the grating processing system comprises a femtosecond laser system, aperture, optical attenuator, cylindrical lens, and phase mask. The spectrum testing system comprises an amplified spontaneous emission (ASE) broadband light source and an optical fiber spectrum analyzer. The laser system outputs 800 nm femtosecond laser pulses. A diaphragm and optical attenuator are used to control the spot diameter and adjust the laser pulse energy, respectively. Meanwhile, a cylindrical lens is used to focus the light beam, and a phase mask to form interference fringes and periodic structures in the fiber, and writing the gratings. In addition, a spectral testing system is used to monitor the spectral changes of the FBG in real time. In the experiment, when the laser energy is set to 600 mW and the longest exposure time is set to 240 s, the influence of exposure time on the FBG reflection spectrum is studied. Moreover, the relationship between the spectral properties and exposure time is analyzed under laser energy values of 700 mW and 800 mW. Results and Discussions The influence of the exposure time on the FBG reflection spectrum is as follows. As shown in Fig. 2(a), when the exposure time increases, the FBG reflectivity gradually increases and then remains unchanged, and the wavelength undergoes a red shift. At the initial exposure time of 20 s, the FBG reflectivity reaches 11.6 dB rapidly, and then, at the exposure time of 75 s, reaches a maximum of approximately 14.03 dB, as shown in Fig. 2(b). Meanwhile, the bandwidth of the FBG increases with the exposure time, which increases from 0.41 nm to 0.73 nm in the exposure timer ange of 5?240 s, as displayed in Fig. 2(c). The FBG wavelength has a red shift as the exposure time increases and the wavelength changes by 0.36 nm, from 1549.33 nm to 1549.69 nm, as the exposure time increases from 5 s to 240 s, as shown in Fig. 2(d). Conclusions In this paper, FBGs fabricated using the femtosecond laser phase-mask method are proposed. The effects of laser energy and exposure time on the wavelength, reflectivity, and bandwidth are studied. The experimental results demonstrate that to obtain FBGs with a small bandwidth, high reflectivity, and high spectral quality, appropriate laser energy and exposure time should be selected. In particular, the laser energy should not be considerably large. Considering the writing efficiency and reflection spectral quality, an excellent FBG device can be obtained by selecting the laser energy of approximately 600 mW and exposure time of less than 1 min.
