Elastic mesh technique for 3D BIM simulation with an application to underwater explosion bubble dynamics

The proposed elastic mesh technique (EMT) is a mesh regulation technique, which is based on the assumption that the segments of a mesh are elastic. EMT can be employed in conjunction with the boundary integral method (BIM) for the simulation of three-dimension bubble dynamics in which problems relating to severe mesh distortion as the bubble evolves are a common occurrence. With EMT, the mesh is advanced not by the material velocity, but the optimum shift velocity obtained by minimizing the total elastic energy stored in every segment of the mesh at each time step. In doing so, the prohibitively small time stepping associated with small meshes without EMT in order to maintain numerical stability is mitigated to a large extent. An important feature is that the EMT scheme accords the user the flexibility to implement a non-uniform optimum constitutive relation governing the elastic behavior of mesh segment and which can be further varied with time. Tests were performed for an underwater explosion bubble exhibiting the dynamics of strong jet development with and without EMT for comparison, and the consideration of incorporating EMT as a hybrid system serving as an alternative to the required mesh refinement which is computationally intensive. A full three-dimension simulation of explosion bubble(s) and in the presence of the free surface were further carried out to elucidate the associated flow physics.     

Feature extraction using rough set theory and genetic algorithms—an application for the simplification of product quality evaluation

Feature extraction is an important aspect in data mining and knowledge discovery. In this paper an integrated feature extraction approach, which is based on rough set theory and genetic algorithms (GAs), is proposed. Based on this approach, a prototype feature extraction system has been established and illustrated in an application for the simplification of product quality evaluation. The prototype system successfully integrates the capability of rough set theory in handling uncertainty with a robust search engine, which is based on a GA. The results show that it can remarkably reduce the cost and time consumed on product quality evaluation without compromising the overall specifications of the acceptance tests.     

Line balancing of PCB assembly line using immune algorithms

Printed Circuit Boards (PCBs) are widely used in most electronic devices. Typically, a PCB design has a set of components that needs to be assembled. In a broad sense, this assembly task involves placing PCB components at designated location on a PCB board; fixing PCB components; and testing the PCB after assembly operation to ensure that it is in proper working order. The stringent requirements of having a higher component density on PCBs, a shorter assembly time, and a more reliable product prompt manufacturers to automate the process of PCB assembly. Frequently, a few placement machines may work together to form an assembly line. Thus, the application of more than one machine for component placement on a PCB presents a line-balancing problem, which is basically concerned with balancing the workload of all the machines in an assembly line. This paper describes the application of a new artificial intelligence technique known as the immune algorithm to PCB component placement as well as the line balancing of PCB assembly line. It also includes an overview of PCB assembly and an outline of the assembly line balancing problem. Two case studies are used to validate the IA engine developed in this work. The details of IA, the IA engine and the case studies are presented.     

Medical image authentication using SLT and IWT schemes

Over the years, different watermarking techniques have been used for medical image authentication purposes. Some techniques have been presented to detect tampering in the medical image while others can also recover the tampered region after the tamper detection. Many of the previous medical image authentication schemes have successfully achieved their aims; however, the robustness of the authentication scheme against unintentional attacks has not been highlighted sufficiently. This paper presents a new medical image authentication scheme in which the medical image is divided into two regions (i.e., region of interest (ROI) and region of non-interest (RONI)). Then two watermarking methods based on Slantlet transform (SLT) are used to embed data in the ROI and the RONI. The proposed scheme can be used for tamper detection, localization, and recovery in addition to the data hiding. To generate the recovery information of the ROI, a new method has been proposed based on the integer wavelet transform (IWT) coefficients. The experiments that have been conducted to evaluate the proposed authentication scheme proved that it is efficient not only in achieving its main tasks that have been mentioned above but also in having robustness against unintentional attacks (i.e., JPEG compression, additive Gaussian noise (AGN), and salt-and-pepper noise) and that makes it more suitable for the practical applications.     

Robust finite-time tracking control of nonholonomic mobile robots without velocity measurements

The problem of robust finite-time trajectory tracking of nonholonomic mobile robots with unmeasurable velocities is studied. The contributions of the paper are that: first, in the case that the angular velocity of the mobile robot is unmeasurable, a composite controller including the observer-based partial state feedback control and the disturbance feed-forward compensation is designed, which guarantees that the tracking errors converge to zero in finite time. Second, if the linear velocity as well as the angular velocity of mobile robot is unmeasurable, with a stronger constraint, the finite-time trajectory tracking control of nonholonomic mobile robot is also addressed. Finally, the effectiveness of the proposed control laws is demonstrated by simulation.     

Tool condition monitoring using reflectance of chip surface and neural network

A wide variety of tool condition monitoring techniques has been introduced in recent years. Among them, tool force monitoring, tool vibration monitoring and tool acoustics emission monitoring are the three most common indirect tool condition monitoring techniques. Using multiple intelligent sensors, these techniques are able to monitor tool condition with varying degrees of success. This paper presents a novel approach for the estimation of tool wear using the reflectance of cutting chip surface and a back propagation neural network. It postulates that the condition of a tool can be determined using the surface finish and color of a cutting chip. A series of experiments has been carried out. The experimental data obtained was used to train the back propagation neural network. Subsequently, the trained neural network was used to perform tool wear prediction. Results show that the prediction is in good agreement with the flank wear measured experimentally.     

Use of oral and intravenous ondansetron in patients treated with cisplatin

Ondansetron, a selective 5-HT3 antagonist, has been shown to be effective in preventing chemotherapy-induced nausea and vomiting. From July and August 1991, 25 patients were accrued in a phase II study to assess the efficacy of ondansetron in patients receiving cisplatin-containing chemotherapy. Patients received intravenous cisplatin 100 mg/m2, given either as a 24-hour infusion on day 1 or in divided doses as eight-hour infusions daily on days 1 to 3. Each patient received 24 mg of ondansetron per day for six days. Intravenous dexamethasone 24 mg was given daily on the days of cisplatin infusion. The emetic episodes and degree of nausea were evaluated daily. "Good" control of emesis (0-2 episodes of vomiting) and nausea (mild or no nausea) ranged from 64-100% and 88-100% respectively. Failure in emesis control occurred most frequently on days 3 and 4. Ondansetron was generally well tolerated with only minimal side-effects. One patient developed unexplained encephalopathy which resolved completely. Our results suggest that ondansetron is an effective anti-emetic agent with minimal toxicities. Randomised studies comparing ondansetron against "standard" anti-emetics should be conducted.     

A cubic RSA code equivalent to factorization

The RSA public-key encryption system of Rivest, Shamir, and Adelman can be broken if the modulus, R say, can be factorized. However, it is still not known if this system can be broken without factorizing R. A version of the RSA scheme is presented with encryption exponent e 3 (mod 6). For this modified version, the equivalence of decryption and factorization of R can be demonstrated.Research supported in part by a grant from the ATERB.Research supported in part by a grant from the ACRB.