Research on the Three-dimensional Modeling and Optimization of a Virtual Tower Crane Based on 3DS Max, Solidworks and EON Professional

Three-dimensional modeling of virtual hoisting machinery is the critical works to structure the system of virtual construction, and the foundation to realize intelligent and interactive virtual hoisting. Aimed at enhancing the requests of image quality and stability of the virtual construction scene, taking a tower crane for example. We studied the technology of three-dimensional modeling and optimization of a virtual tower crane, and a method named two-stage model optimization was put forward. This depended on the modeling stage using Solidworks and 3DS Max and the performance optimization stage in EON. The practice of software development indicates that the proposed methods of three-dimensional modeling and optimization could satisfy the performance request of virtual construction system and be popularized to other virtual system.

Three-dimensional suboptimal guidance law for fly-over and shoot-down smart ammunition via virtual target

An optimal burst height is required for the fly-over and shoot-down smart ammunition with an EFP warhead at the instant of explosion which brings a special requirement to the miss distance of the terminal guidance law. In this paper, a guidance law based on the virtual target scheme is proposed. First, the practical pursuit-evasion issue between the ammunition and the target with specific miss distance is transformed into a virtuai pursuit-evasion problem with zero miss distance. Secondly, a complete three-dimensional pursuit-evasion kinematics model is established without any simplifications. And then, a suboptimal guidance law is designed based on the θ-D method which has constraints of the elevation and azimuth angular velocity of the virtual line of sight （LOS）. Finally, in order to verify the performance of the proposed guidance law, three test cases are conducted. Numericai results show that under the proposed terminal guidance law, the smart ammunition not only can fly above the target with an optimal burst height but also have a smaller normal acceleration on the terminal trajectory.

Numerical study on three-dimensional flow field of continuously rotating detonation in a toroidal chamber

Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.

A combined numerical model of three-dimensional tidal motion and sediment transport in tidal current and its application

A calculation scheme, which combines a horizontal upwind finite element method with vertical implicit differences, is used to establish a three-dimensional mathematical model of tidal motion and sediment transport in tidal current. Compared with those of the relative theoretical formula, the results are satisfactory. The model mentioned above has been applied to the water area of the Lianzhou Bay, Guangxi Province. On the basis of the analysis and comparison with the field data, it shows clearly that the model calculation results are reasonable.

Three-Dimensional Instability of Flow Around Two Circular Cylinders in Tandem Arrangement

The spatial evolution of vortices and transition to three-dimensionality in the wake of two circular cylinders in tandem arrangement have been numerically studied. An improved virtual body method developed from the virtual boundary method is used here. A Reynolds number range between 220 and 270 has been considered, and the spacing between two cylinders is selected as L/D=3 and L/D=3.5. When L/D=3, the secondary vortices of Mode-A are seen to appear at Re=240 and persist over the range of the Reynolds number of 240～270. When L/D=3.5, the similar critical Reynolds number has been found at Re=250. No obvious discontinuity has been found in the Strouhal-Reynolds number relationship, and this is different from three-dimensional flow around a single cylinder at the critical Reynolds number. The spanwise wavelength is about four times the diameter of the cylinder, and it is the characteristic wavelength for Mode-A instability. This paper can give some foremost insight into the three-dimensional instability of flow by complicated geometrical configuration.

Application of Three-Dimensional Visualization Technology in Project Management of Offshore Platform Engineering Construction

Three-dimensional visualization technology converts engineering design drawings and data into graphics or images, realizes virtual reality perception of simulated users in future construction scene, enhances the interaction between project management and technical personnel and engineering construction achievement, and provides intuitive, flexible and strong realistic experience for project management. It can effectively improve the level of project communication, and assist the needs of project construction planning management, training, exhibition, etc. As a tool to help improve project management skills, it has good application effect and prospects.

3-Dimensional Body Measurement Technology

3 - dimensional body measurement technology, the basis of developing high technology in industry, accelerates digital development of aplparel industry. This paper briefly introduces the history of 3 - dimensional body measurement technology, and recounts the principle and primary structure of some types of 3 - dimensional automatic body measurement system. With this understanding, it discusses prospect of 3- dimensional CAD and virtual technology used in apparel industry.

A Sensor Awakening Algorithm for Wireless Multimedia Sensor Networks Three Dimensional Target Tracking

For node awakening in wireless multi-sensor networks, an algorithm is put forward for three dimensional tar- get tracking. To monitor target dynamically in three dimensional area by controlling nodes, we constract vir- tual force between moving target and the current sense node depending on the virtual potential method, then select the next sense node with information gain function, so that when target randomly move in the specific three dimensional area, the maximum sensing ratio of motion trajectory is get with few nodes. The proposed algorithm is verified from the simulations.

A MULTISCALE MECHANICAL MODEL FOR MATERIALS BASED ON VIRTUAL INTERNAL BOND THEORY

Only two macroscopic parameters are needed to describe the mechanical properties of linear elastic solids, i.e. the Poisson＇s ratio and Young＇s modulus. Correspondingly, there should be two microscopic parameters to determine the mechanical properties of material if the macroscopic mechanical properties of linear elastic solids are derived from the microscopic level. Enlightened by this idea, a multiscale mechanical model for material, the virtual multi-dimensional internal bonds （VMIB） model, is proposed by incorporating a shear bond into the virtual internal bond （VIB） model. By this modification, the VMIB model associates the macro mechanical properties of material with the microscopic mechanical properties of discrete structure and the corresponding relationship between micro and macro parameters is derived. The tensor quality of the energy density function, which contains coordinate vector, is mathematically proved. From the point of view of VMIB, the macroscopic nonlinear behaviors of material could be attributed to the evolution of virtual bond distribution density induced by the imposed deformation. With this theoretical hypothesis, as an application example, a uniaxial compressive failure of brittle material is simulated. Good agreement between the experimental results and the simulated ones is found.

Virtual endoscopy of the urinary tract

Technological breakthroughs have advanced the temporal and spatial resolutions of diagnostic imaging, and 3 dimensional （3-D） reconstruction techniques have been introduced into everyday clinical practice. Virtual endoscopy （VE） is a non-invasive technique that amplifies the perception of cross-sectional images in the 3-D space, providing precise spatial relationships of pathological regions and their surrounding structures. A variety of computer algorithms can be used to generate 3-D images, taking advantage of the information inherent in either spiral computed tomography or magnetic resonance imaging （MRI）. VE images enable endoluminal navigation through hollow organs, thus simulating conventional endoscopy. Several clinical studies have validated the diagnostic utility of virtual cystoscopy, which has high sensitivity and specificity rates in the detection of bladder tumor. Published experience in the virtual exploration of the renal pelvis, ureter and urethra is encouraging but still scarce. VE is a safe, non-invasive method that could be applied in the long-term follow-up of patients with ureteropelvic junction obstruction, urinary bladder tumors and ureteral and/or urethral strictures. Its principal limitations are the inability to provide biopsy tissue specimens for histopathologic examination and the associated ionizing radiation hazards （unless MR/is used）. However, in the case of endoluminal stenosis or obstruction, VE permits virtual endoluminal navigation both cephalad and caudal to the stenotic segment. To conclude, VE provides a less invasive method of evaluating the urinary tract, especially for clinicians who are less familiar with cross-sectional imaging than radiologists. （Asian J Androl 2006 Jan; 8： 31-38）

Ultrasound virtual endoscopy: Polyp detection and reliability of measurement in an in vitro study with pig intestine specimens

AIM: To present our initial experience regarding the feasibility of ultrasound virtual endoscopy(USVE) and its measurement reliability for polyp detection in an in vitro study using pig intestine specimens.METHODS: Six porcine intestine specimens containing 30 synthetic polyps underwent USVE, computed tomography colonography(CTC) and optical colonoscopy(OC) for polyp detection. The polyp measurement defined as the maximum polyp diameter on twodimensional(2D) multiplanar reformatted(MPR) planes was obtained by USVE, and the absolute measurement error was analyzed using the direct measurement as the reference standard.RESULTS: USVE detected 29(96.7%) of 30 polyps, remaining a 7-mm one missed. There was one falsepositive finding. Twenty-six(89.7%) of 29 reconstructedimages were clearly depicted, while 29(96.7%) of 30 polyps were displayed on CTC with one false-negative finding. In OC, all the polyps were detected. The intraclass correlation coefficient was 0.876(95%CI: 0.745-0.940) for measurements obtained with USVE. The pooled absolute measurement errors ± the standard deviations of the depicted polyps with actual sizes ≤ 5 mm, 6-9 mm, and ≥ 10 mm were 1.9 ± 0.8 mm, 0.9 ± 1.2 mm, and 1.0 ± 1.4 mm, respectively.CONCLUSION: USVE is reliable for polyp detection and measurement in in vitro study.

Design of a 6 DOF Input Device in Telerobotics and Virtual Reality

The pincipl of a 6 DOF (degress of freedom) input device using ultrasonic distance measurement is presented in this paper. The system employs the method of measuring the time of flight. In addition, some techniques, including automatic gain control, self-adaptive variable threshold and temperature compensation, are also used to improve precision. Then, the positions and orientation of the input device can be calculated by the method of spatial analytic geometry. Meanwhile, commands from the 3-D input device are detected and carried out. The validity and precision of the input device are verified by the experiment in a robot system. The proposed device not only can be used for end effector position and orientation measurement in telerobotics, but also can be an interactive device in virtual reality systems, such as helmet tracking, viewpoint navigation and object manipulation.

A Virtual Erection Simulation System for a Steel Structure Based on 3-D Measurement Data

he virtual erection simulation system was explained for a steel structure including ship and ocean plant blocks. The simulation system predicted the erection state to optimize any gap or overlap of blocks based on 3-D measurement data. The blocks were modified （cut） on the basis of the simulation result on the ground before erecting them by crane. The re-cutting process was not required and the blocks were erected into a mother ship speedily. Therefore, the erection time is reduced, increasing the dock turnover.

混合现实技术在口腔颌面部肿瘤诊疗中的应用

口腔颌面部肿瘤是口腔颌面外科的常见疾病,以虚拟手术设计、手术导航为代表的数字化外科技术目前已成为口腔颌面部肿瘤外科诊治的主要辅助手段。然而,现有的数字化技术在三维可视化成像、术中手眼配合等方面仍存在提升空间。目前,以混合现实技术为代表的三维可视化技术已经在医学领域迅速发展和应用,通过将三维虚拟图像叠加到真实的手术环境中,可辅助实现医学影像实时立体呈现,已逐步应用于口腔颌面部肿瘤的诊治中。术前可基于影像数据构建肿瘤及其周边重要结构三维模型,在混合现实环境中,进行个性化术前评估和手术方案设计;术中将混合现实技术与手术导航技术相结合,可以在术区真实环境中实时显示三维虚拟模型,克服单纯使用导航技术的手眼协调问题,进一步提高口腔颌面部肿瘤手术的精确性和安全性。混合现实技术与远程互联网医疗技术相结合,还可以提供高质量的教学平台,推动地区口腔颌面外科诊疗水平的发展。混合现实技术的局限性主要在于术区影像遮挡、单纯使用时精度不足、配准时间长等。笔者结合国内外文献报道以及本课题组的临床实践,对混合现实技术在口腔颌面部肿瘤诊疗中的应用进行归纳与总结。

Training benefits of virtual bronchoscopy prior to Endobronchial Ultrasound Guide sheath

Research questions. How does a virtual bronchoscopy navigation system (VBNS) improve prediction of candidate bronchus across a range of doctors investigating a range of lesions with Endobronchial ultrasound (EBUS) guide sheath? To what extent do benefits of virtual bronchoscopic pre-procedure navigation apply to experienced versus inexperienced bron- choscopists? Methods: Using archived EBUS Guide sheath cases, a comparison was made between identified candidate 4th order bronchus by Computerised tomography (CT) evaluation versus that identified after virtual path creation. Results: From 7 archived cases, 14 doctors identified the correct bronchus in 94 of 98 assessments (95%). Percentage of cases where there was an improvement in localisation by 2 or more 4th order bronchi was 39.8% overall (28.6% – 51.0%), 26.6 for experienced and 53.1 for inexperienced bronchoscopists (p < 0.02). The absolute mean number of 4th order bronchi different between CT and VBNS was 2.0 ± 2.6 overall, 1.2 (range 0-6) for experienced, and 2.8 (range 0-11) for inexperienced bronchoscopists. Virtual Path software calculation time was 8.1 ± 2.7 minutes, compared to 3.6 ± 2.1 minutes by CT. Conclusion: VBNS allowed rapid accurate assessment with minimal software training. Greatest benefits in reduction of procedure time were obtained in inexperienced bronchoscopists, and VBNS could allow more rapid skill development in EBUS GS in these doctors.

虚拟仿真技术联合PBL教学法在心脏超声住院医师规范化培训中的应用

目的探讨运用虚拟仿真技术结合PBL教学模式在心脏超声学科住院医师规范化培训中的应用效果。方法将59名参加规范化培训的住院医师分为试验组(n=31)和对照组(n=28)。其中,试验组采用虚拟仿真技术联合PBL教学法,对照组采用传统教学法开展教学。教学效果从理论考核、临床思维考核、技能考核及满意度问卷调查等方式进行评价。结果试验组在理论知识、临床思维和操作技能的考核成绩及教学满意度的评价显著优于对照组。结论虚拟仿真技术联合PBL教学法用于心脏超声学科住院医师规范化培训具有明显的优势,可提升教学质量和效果,激发学生学习的主动性和创造力,值得进一步推广。

多感官体验下三维虚拟交互式水墨动画的设计与制作

水墨画是纯用水墨进行艺术创作的绘画种类,具有独特的审美意蕴、丰富的动作艺术语言和不拘一格的表现形式。三维虚拟交互技术对水墨画形式创新提供了支持,借助三维制作软件、虚拟交互制作软件、平面及后期制作软件,三维虚拟交互式水墨动画的艺术特质更为凸显。三维虚拟交互式水墨动画设计实践包括基于内容题材及视觉元素的设计实践、基于角色模型及分镜构图的设计实践两大类,在制作过程中应按照基础模型的设定及动画制作、水墨渲染效果的制作、虚拟三维环境下动态交互效果的制作的流程加以实施。

智能手机联合VR虚拟现实手术视频在泌尿外科教学中的应用

目的探索基于智能手机和虚拟现实(virtual reality,VR)设备的虚拟现实技术应用于泌尿外科手术的教学效果。方法将2021年1月至2022年1月大连医科大学临床医学院的30名学生作为研究对象,采用理论学习联合应用VR头戴设备+智能手机学习腹腔镜膀胱癌根治性切除手术视频的学习模式,学习后应用李克特量表的评估表评估教学效果和对这种教学工具的积极和消极因素进行测试。结果30名学生均对学习进行评价,27名(90.9%)认为3D视频教学提高了他们对手术步骤的理解,28名(93.3%)认为视频提供了很好的解剖结构的三维可视化,30名(100%)均认为3D视频提高了对解剖关系的理解,26名(86.7%)对三维视频的易用性和体验持积极态度,并认为比常规的讲座更有信息量,27名(90.9%)喜欢使用VR看手术视频,29名(96.7%)认为3D视频是一个很好的教学工具。30名(100%)全部认为3D手术视频应该包括在常规的泌尿外科教学中。结论智能手机和VR设备的虚拟现实技术在泌尿外科教学中的应用,为新形势下教学模式的探索打开了新思路,有利于提高学生参与度及学习效果,可在泌尿外科教学中尝试试行。

考虑电力网络约束的工业园区虚拟电厂调控边界求解方法

构建以新能源为主体的新型电力系统,亟须挖掘负荷侧灵活调节资源参与电网调控。含电解铝、矿热炉等高耗能负荷的工业园区具备良好的调控潜力,但是考虑园区内部电力网络约束,其精确调控边界求解面临着变量维数高、约束非线性的难题,现有方法不能较好地兼顾计算效率和精度。对此,文中将上述问题抽象为高维非线性状态空间在P-Q耦合平面的投影问题:分别建立考虑工业园区安全运行线性化和非线性约束的调控边界投影求解模型,采用一种新颖的高维状态空间投影算法,通过顶点“搜索-映射”的两步式求解过程,得到工业园区型虚拟电厂调控边界的精确投影。算例结果表明,采用所提方法求解的调控边界可由线性不等式组完全表征,与现有调度系统完全兼容,结合与叠加柔性资源调控能力和传统采样方法的对比,验证了该方法的可行性以及高求解精度和效率。