Effect of global position information in unknown world exploration — A case study using the Teleworkbench

This paper presents empirical results of the effect of the global position information on the performance of the modified local navigation algorithm (MLNA) for unknown world exploration. The results show that global position information enables the algorithm to maintain 100% success rate irrespective of initial robot position, movement speed, and environment complexity. Most mobile robot systems accrue an odometry error while moving, and hence need to use external sensors to recalibrate their position on an ongoing basis. We deal with position calibration to compensate the odometry error using the global position information provided by the Teleworkbench, which is a teleoperated platform and test bed for managing experiments using mini-robots. In this paper we demonstrate how we incorporate the global position information during and after the experiments.     

Physical properties of ultrafast deposited micro- and nanothickness amorphous hydrogenated carbon films for medical devices and prostheses

Hydrogenated amorphous carbon films with diamond-like structures have been formed on different substrates at very low energies and temperatures by a plasma-enhanced chemical vapour deposition (PECVD) process employing acetylene as the precursor gas. The plasma source was of a cascaded arc type with argon as the carrier gas. The films grown at very high deposition rates were found to have a practical thickness limit of approximately 1.5 microm, above which delamination from the substrate occurred. Deposition on silicon (100), glass, and plastic substrates has been studied and the films characterized in terms of sp3 content, roughness, hardness, adhesion, and optical properties. Deposition rates of up to 20 nm/s have been achieved at substrate temperatures below 100 degrees C. A typical sp3 content of 60-75 per cent in the films was determined by X-ray-generated Auger electron spectroscopy (XAES). The hardness, reduced modulus, and adhesion of the films were measured using a MicroMaterials NanoTest indenter/scratch tester. Hardness was found to vary from 4 to 13 GPa depending on the admixed acetylene flow and substrate temperature. The adhesion of the film to the substrate was significantly influenced by the substrate temperature and whether an in situ d.c. cleaning was employed prior to the deposition process. The hydrogen content in the film was measured by a combination of the Fourier transformation infrared (FTIR) spectroscopy and Rutherford backscattering (RBS) techniques. From the results it is concluded that the films formed by the process described here are ideal for the coating of long-term implantable medical devices, such as prostheses, stents, invasive probes, catheters, biosensors, etc. The properties reported in this publication are comparable with good-quality films deposited by other PECVD methods. The advantages of these films are the low ion energy and temperature of deposition, ensuring that no damage is done to sensitive substrates, very high deposition rates, relatively low capital cost of the equipment required, and the ease of adjustment of plasma parameters, which facilitates film properties to be tailored according to the desired application.     

Sum of Sinusoids Simulator for Millimeter Wave Channel Model Towards 5G Networks

The aspirations of users to expand their data rate up to 1 Gbps in the fifth generation (5G) mobile networks open the horizon to exploit the row bandwidths in the millimeter wave (mmW) frequency bands. Several measurement campaigns have been launched to calculate the power delay profile and the large scale fading of the channels (path loss, shadowing) in mmW bands. In this paper, we design a 3D mmW multi-input multi-output channel model to extract the analytical narrowband impulse response. Based on a reference model, we establish a Sum-of-Sinusoids channel simulator in mmW frequency bands that is capable of generating the channel impulse response, which reflects the real conditions. The numerical results illustrate the outcomes of the simulator at different mmW frequency bands.     

Straightness and flatness tolerance evaluation: an optimization approach

This paper presents an optimization approach that could be used to calculate exact values of straightness and flatness errors as defined by the ANSI Y14.5M standards on geometric dimensioning and tolerancing. The straightness and flatness error evaluation problems are formulated as nonlinear optimization problems with linear objective function and nonlinear constraints. Because of the special structure of the problem, a linear search method is developed that reduces the nonlinear problem to a linear programming problem with only two constraints. Examples are presented to compare the optimization approach with the least-squares method and some exact methods. The results show that the optimization procedures presented in this paper provide exact values of straightness and flatness errors and are superior to the existing methods in terms of computation time.     

The real cost of air conditioning load

The significance of the air conditioning load and its impact on the daily fuel cost of electric power networks have been pointed out. A model has been developed for assessing the increase in the daily fuel cost due to the A/C load, taking into account both the system load characteristics (peak load, load factor, generation cost) as well as the parameters of the added air conditioning load (A/C peak load, starting time and its duration). The model allows for the consideration of two different control procedures used for reducing the daily cost of the power network's fuel consumption: delaying the A/C load starting time; and the utility-controlled disconnection of the A/C load for several minutes per hour. The simultaneous application of both strategies can be also simulated and economically assessed     

A new method for grafting functional groups onto mesoporous silica: an electrochemical approach

A novel method for the modification of mesoporous silica, MCM-41, using an electrochemical approach has been developed, and the process was monitored by cyclic voltammetery and spectrometric methods. The method was applied to the modification of mesoporous silica with new functional groups which are not accessible by conventional methods. Malononitrile-functionalized MCM-41 mesoporous silica was characterized by low-angle X-ray diffraction, Fourier transform infrared spectroscopy, mass spectrometry, thermal analysis, elemental analysis, high resolution transmission electron microscopy, and surface area measurement (S _BET). In addition, the application of malononitrile-functionalized MCM-41 as a sorbent for gold ions was demonstrated.