近似软影下的三维增强绘制

针对目前的三维增强绘制方法尚未涉及阴影效果这一现象,提出一种新的包含近似软影效果的三维增强绘制算法.针对简单光照场景,设计了一种新的尺度函数,应用该尺度函数调整每个像素的光亮度值,使得物体的表面细节看上去更加凸显;在此基础上引入近似软阴影效果,利用GPU的几何着色器提取物体的轮廓边生成近似半影区,通过调整半影区的衰减参数来控制半影区的大小和亮度,可以使软阴影变得更黑更集中.实验表明应用该方法可以得到整个三维场景一致增强的效果.     

3D printed deformable product handle material for improved ergonomics

In product handle ergonomic design optimisation researchers focused mainly on the size and shape of the handles; however, interface handle materials have been neglected despite showing potential to improve ergonomics. Deformable elastic cellular meta-materials with pre-engineered mechanical response based on the biomechanical evaluation of human hand soft tissue during grasping were designed and manufactured using commercial 3D printing technology. A sawing task has been utilized for the evaluation of subjective comfort rating. Based on distinct mechanical behaviour of cellular solids, 3D printed handle interface material stays stiff at the low grasping forces and deforms only when certain amount of contact pressure is reached. Cellular density can be easily adjusted to meet the desired biomechanical response. Hereby stability of the handle in hands is maximised while providing more uniform contact pressure distribution on the soft tissue at higher grasping forces. By this means comfort rating is also increased compared to stiff handle interface materials such as plastic. Results also suggest the handle material has greater influence on the comfort rating than the handle size and shape.Relevance to industryApplication of this research includes the utilization of this methodology and design techniques in development of handles for powered and non-powered tools and handheld products for improved comfort and also ergonomics.     

Fundamental characteristics of printed gelatin utilizing micro 3D printer

Gelatin is useful for biofabrication, because it can be used for cell scaffolds and it has unique properties. Therefore, we attempted to fabricate biodevices of gelatin utilizing micro 3D printer which is able to print with high precision. However, it has been difficult to fabricate 3D structure of gelatin utilizing 3D printer, because a printed gelatin droplet on the metal plate electrode would spread before solidification. To clear this problem, we developed a new experimental set-up with a peltier device that can control temperature of the impact point. At an impact point temperature of 80 °C, the spreading of printed gelatin droplets was prevented. Therefore, we were able to print a ball gelatin. In addition, we were able to print a narrower gelatin line than at an impact point temperature of 20 °C.     

A 3D printed centrifugal microfluidic platform for automated colorimetric urinalysis

Colorimetric urinalysis is a commonly performed test for rapid and low-cost diagnosis. Conventional colorimetric urinalysis is manually conducted using dipsticks and suffers from difficulties in control of sample distribution and color interpretation. This paper reports a microfluidic platform for conducting automated colorimetric urinalysis. Centrifugal microfluidic technology was used for regulating the distribution of urine sample in designed volume and time sequence. The prototype of the microfluidic chip was fabricated using 3D printing technology. To test the feasibility of the prototype system, commercial urinalysis strips were integrated with the microfluidic system for detecting glucose, specific gravity, PH, and protein from simulated urine sample. The color change of the strips was recorded using a smartphone and analyzed to quantify the interested parameters. The H (hue), S (saturation) and V (value) coordinates of the HSV color space were extracted and related to the change of the four parameters. The intensity change of V channel showed good representation of the change of glucose concentration and specific gravity. The intensity change of S channel decreased as the increase of PH and protein concentration. The proposed Lab-on-CD platform has potential for automating colorimetric urinalysis to reduce the user errors, thus to made the testing results conducted by non-professionals more reliable.

     

三维烟雾的实时模拟

提出了一种基于流体力学方程并采取欧拉法实时模拟三维真实感烟雾的算法。通过Navier-Stokes方程建立烟雾流场的物理模型,以保证视觉的真实感。为了保证运算的实时性,烟雾流场划分为三维网格空间,并将烟雾速度场的分布定义于每个立方网格单元的中心点;通过线性插值获取整幅图像中每个像素的烟雾浓度。将烟雾模拟技术用于图像的显示特技中,以产生图像消散成烟雾的视觉效果,得到了比较满意的模拟效果。     

Reinforced steel I-beams: A comparison between 2D and 3D simulation

This study reports the accuracies of Finite Element (FE) simulations, based on two and three dimensional (2D and 3D) modelling of strengthened steel I-beams in static linear and non-linear analyses. To investigate the effects of simulation modelling methods on the accuracy of the results, 28 computer and laboratory specimens were used. To strengthen the beams, Carbon Fibre Reinforced Polymer (CFRP) and steel plates were applied, and to simulate the specimens, ANSYS software was utilized. All specimens were modelled by using shell elements or solid elements in the 2D and 3D modelling cases, respectively. The results show that non-linear and 3D simulation methods predicted the experimental results appropriately.     

Design and simulation of an ultrasonic linear motor with dual piezoelectric actuators

In this study, an ultrasonic linear motor with dual piezoelectric (PZT) actuators is developed. A traveling wave motion is generated on the stator by a double-sided excitation of the stator of the ultrasonic linear motor, which drives the slider that is connected to the stator. The development and design processes are described. In this paper, the principle of using an ultrasonic motor to drive a traveling wave type is presented. The structure for the ultrasonic linear motor is then demonstrated with its dimensions, driving conditions and material parameters, so that Computer-Aided Engineering (CAE) can be used to simulate the driving performance. The simulation results show the differences to the characteristics that are achieved by adjusting the critical parameters, such as the PZT boned positions, the excitation frequency and the preload, in order to derive the best design. A prototype that uses the best parameter design is presented, and a method to improve development processes is presented in the final section.

     

弯线机工件加工动作的三维仿真

利用线材折弯的数学模型,通过离散化的方法,并根据OpenGL动画的工作原理,实现了在二维平面和三维空间多种几何线材的实物造型,设计了软件操作界面,能够通过键盘来控制三维模型的视角。     

3D road traffic situation simulation system

The 3D traffic situation simulation system combines the multibody based mathematical model of a vehicle, the multibody mathematical model of human body, the database of vehicle and human body data and the display subsystem. Together with the model of driving surface the system can be used to simulate and analyse vehicle and its occupant behaviour under different road conditions and different driving regimes. The result obtained this way can be used to investigate safety related parameters and optimise the driver–vehicle–road system regarding to arbitrary criteria (safety, comfort, speed, etc.). The results of simulations are available as numerical data as well as animations in virtual 3D environment.     

Automated adaptive 3D forming simulation processes

In this study, an automated adaptive mesh control scheme, based on local mesh modifications, is developed for the finite element simulations of 3D metal-forming processes. Error indicators are used to control the mesh discretization errors, and an h-adaptive procedure is conducted. The mesh size field used in the h-adaptive procedure is processed to control the discretization and geometric approximation errors of the evolving workpiece mesh. Industrial problems are investigated to demonstrate the capabilities of the developed scheme.     

Sliding-based image-guided 3D needle steering in soft tissue

This paper presents a sliding-based method for steering beveled-tip needles in a 3D environment. The controller determines the needle roll angle using the needle tip position deviation, obtained from ultrasound images, and its first time derivative. The stability of the closed-loop system is analyzed using 3D unicycle model for the needle, as a result of which parameter constraints are derived. In this method the needle is steered by performing adjustments of needle orientation, which reduces the tissue trauma and injury. The performance of this method is verified by performing experiments using phantom tissue for environments with and without obstacles.     

结合三维视景的自定义位图动画实现

作为激光传输系统的关键环节,激光传输的建模和仿真具有重要意义.提出了一种利用三维视景的自定义位图动画实现激光传输仿真的新方法,该方法首先通过调用动态链接库将三维虚拟仿真与传统的二维数值模拟相结合,然后利用鼠标或键盘对虚拟场景中观测点位置或三维模型进行平移或旋转操作实现模型拾取,科技人员可以在看得见,摸得着的情况下修改模型的各个参数,并可以实时或离线显示计算仿真结果.该方法为科技人员提供了良好的人机交互界面,仿真结果也表明了该方法可操作性和有效性.     

Design and development of an efficient fluid mixing for 3D printed lab-on-a-chip

Microsystem Technologies - In this paper, we present elaborate study of design parameters of hybrid microfluidic mixer through numerical approach using finite element method and experimental...     

3D printed dielectric lens for the gain enhancement of a broadband antenna

A novel 3D printed dielectric lens to enhance antenna gain parameters is presented. The lens is fabricated using a fused deposition method (FDM) which is a cost‐effective and an efficient 3D printing technique. Poly‐methyl methacrylate (PMMA) is used as a dielectric material due to its good RF properties. The thickness of the dielectric lens is 14 mm and provides a gain enhancement of up to 6.9 dBi over a wide frequency range. The dielectric lens is designed and computationally analyzed to demonstrate refractive index value close to zero. It has been shown that impedance‐matched near‐zero refractive index lens geometry eliminates strong reflections, and consequently enhances the antenna gain. A correlation is established between the individually, stacked unit cell layers and near‐zero refractive index cut‐off frequencies. The claim is substantiated through measured results using a broadband Vivaldi antenna. A gain enhancement of up to 6.9 dBi is recorded for the bandwidth from 13.5 to 24 GHz. An excellent correlation is reported between the measured and simulated results.     

3D printed acoustic metamaterials with microscale gaps as sound-absorbing mask for the patients of Tourette syndrome

Microsystem Technologies - Tourette syndrome (TS) is an inherited neurophysiologic disorder with onset in childhood, characterized by multiple physical (motor) tics and at least one vocal (phonic)...     

Interactions with 3D isotropic and homogeneous radiation fields: a Monte Carlo simulation algorithm

Monte Carlo techniques have become important tools for many biomedical applications. Many of these involve simulations of radiation fields that rely on the isotropy and homogeneity of the radiation source. The current study proposes a general algorithm to simulate such a radiation field around a fixed object. The idea is to surround the object with a sphere and to limit the source of radiation to the surface of that sphere. To insure the isotropy of the radiation source, each point on the sphere surface as seen from the object defines a direction at which a unidirectional field of particles is created. The combination of all unidirectional fields approaching from all points on the source sphere creates the effect of an isotropic and homogeneous radiation source. The algorithm is first presented without mathematical detail. Next, the expressions for the position and direction of the particles that compose the field are derived using analytical geometry. The radius of the source sphere is the only parameter needed for this algorithm. The randomness of each particle is simulated by the choice of four random numbers. Two algorithms using these analytical results are proposed, and an example of a C program is given for each. Both algorithms can be easily adapted to any situation that involves the Monte Carlo simulation of radiation interactions of a fixed object immersed within an isotropic and homogeneous radiation field.     

A finite element model for the analysis of 3D axisymmetric laminated shells with piezoelectric sensors and actuators: Bending and free vibrations

This paper addresses the bending and free vibrations of multilayered cylindrical shells with piezoelectric properties using a semi-analytical axisymmetric shell finite element model with piezoelectric layers using the 3D linear elasticity theory. In the present 3D axisymmetric model, the equations of motion are expressed by expanding the displacement field using Fourier series in the circumferential direction. Thus, the 3D elasticity equations of motion are reduced to 2D equations involving circumferential harmonics. In the finite element formulation the dependent variables, electric potential and loading are expanded in truncated Fourier series. Special emphasis is given to the coupling between symmetric and anti-symmetric terms for laminated materials with piezoelectric rings. Numerical results obtained with the present model are found to be in good agreement with other finite element solutions.     

基于3D-LBM的多相流快速模拟

对于流体和其他物体的交互, 提出了一种基于Lattice Boltzmann的建模和绘制方法。针对固、液交互提出了外力叠加机制, 考虑了障碍物对流体的单向作用; 在液、液交互时考虑了两种液体的相互作用力。采用GPU硬件加速技术对LBM算法进行了加速, 并采用基于屏幕空间的绘制技术对流体表面进行了绘制。实现了两种不相溶液体交互, 以及液体与固体交互场景的模拟。     

A visual simulation technique for 3D printing

Rapid prototyping technologies can create the physical part directly from the digital model by accumulating layers of a given material. Providing a tremendous flexibility of a part geometry that they can fabricate, these technologies present an opportunity for the creation of new products that cannot be made with existing technologies. One of its capabilities is to fabricate surface texture, which denotes a set of tiny repetitive geometric features on an object surface. In this paper we propose a visual simulation technique involving development of an intermediate geometric model of the surface texture design prior to fabricating the physical model. Careful examination of the visually simulated model before the actual fabrication can help minimize unwanted design iterations. The proposed technique demonstrated visualization capability by comparing the virtual model with the physical model for several test cases.