Development of a unified FDTD-FEM library for electromagnetic analysis with CPU and GPU computing

The present paper describes an optimized C++ library for the study of electromagnetics. The implementation is based on the Finite-Difference Time-Domain method for transient analysis, and the Finite Element Method for electrostatics. Both methods share the same core and are optimized for CPU and GPU computing. To illustrate its running, FEM method is applied for solving Laplace’s equation analyzing the relation between surface curvature and electrostatic potential of a long cylindrical conductor, whereas FDTD is applied for analyzing Thin Film Filters at optical wavelengths. Furthermore, a comparison of the performance of both CPU and GPU versions is analyzed as a function of the grid size simulation. This approach allows the study of a wide range of electromagnetic problems taking advantage of the benefits of each numerical method and the computing power of the modern CPUs and GPUs.     

Total contact casts: pressure reduction at ulcer sites and the effect on the contralateral foot

OBJECTIVE: To compare the effectiveness of total contact casts with a cast boot (TCCB), total contact casts with a cast heel (TCCH), and therapeutic XtraDepth shoes (XDS) to reduce ulcer site pressures and to determine if total contact casts increase contralateral pressures. DESIGN: Repeat measure design with 40 replications nested within each treatment for each patient. METHODS: Peak contralateral foot pressures and ulcer site pressures under the 1st metatarsal (1MET; n = 10), 2nd to 5th metatarsals (2-5MET; n = 10), and great toe (GT; n = 5) were compared using the Novel-Pedar system and three treatments: TCCB, TCCH, and XDS. Baseline pressures were established using canvas oxfords. RESULTS: There was no difference in pressure reduction with TCCH vs. TCCB for 1MET or GT ulcers, but TCCH reduced pressure better for 2-5MET ulcers (p < .001). Contralateral pressures were not elevated in either TCC group. CONCLUSIONS: TCCH were superior to TCCB in reducing 2-5MET ulcer pressures and equivalent to TCCB for 1MET and GT ulcers. Contralateral pressures are not increased by TCC use.     

Data-Fusion Approaches and Applications for Construction Engineering

Data fusion can be defined as the process of combining data or information for estimating the state of an entity. Data fusion is a multidisciplinary field that has several benefits, such as enhancing the confidence, improving reliability, and reducing ambiguity of measurements for estimating the state of entities in engineering systems. It can also enhance completeness of fused data that may be required for estimating the state of engineering systems. Data fusion has been applied to different fields, such as robotics, automation, and intelligent systems. This paper reviews some examples of recent applications of data fusion in civil engineering and presents some of the potential benefits of using data fusion in civil engineering.     

Characterization of polyvinyl alcohol/acrylamide holographic memories with a first-harmonic diffusion model

Several theoretical models have been proposed to predict the behavior of photopolymers as holographic recording materials. Basically these models have been applied to study thin layers (around 100 microm thick). The increasing importance of holographic memories recorded in photopolymers (thickness of > 500 microm) makes it necessary to extend the ideas proposed by these models to study thick photopolymer layers. We calculate the temporal evolution of the diffraction efficiencies for thick layers using a first-harmonic diffusion model, and the results obtained are compared with the corresponding values for thin layers. Furthermore, the values of the average diffusivity of the polymer chains after the grating is formed are also obtained. In general, we find that the monomer and polymer diffusivity increases when higher values of thickness are used.     

Clarifications to the paper "Holographic characteristics of a 1-mm-thick photopolymer to be used in holographic memories"

We have corrected typing errors related to the characterization of the dynamic range of the acrylamide photopolymer described in an earlier study [Appl. Opt. 42, 7008 (2003)]. The M number is expressed as M/# instead of M# as appears in the text. The value calculated from the experimental results that are included in the article is M/# = 3.8 instead of 38 as appears in the text.     

Coffee certification criterion using the photoacoustic technique

The photoacoustic (PA) technique allows a spectroscopic analysis of organic opaque samples and its thermal characterization; so this technique gives information about the pigmentation and the roasting modelling parameters, important for industry and commercialization process, when it is applied to green and powdered coffee samples, respectively. A spectrum is particular of each sample; so is possible to identify different characteristics in coffee powder, for example: purity, caffeine content, roasting level, origin conditions, etc. Powdered coffee PA spectroscopic measurements and correlation analysis that allow proposing a discrimination criterion are reported in this work. Also, the thermal diffusivity of green coffee samples was measured by open cell PA technique, in order to study the relation of this parameter with the bean cellular structure, which was looked through an optical microscopy. The results presented will allow a possible method for certifying organic coffee, which is cultivated without chemicals and has greater price in the international market and positive impact on the environment.     

VSPLIT: A Cross-Layer Architecture for V2I TCP Services Over 802.11

This article proposes VSPLIT, a new architecture based on TCP cross-layering and splitting techniques for optimizing the transport layer performance in vehicular networks for Internet-based Vehicle-to-Infrastructure (V2I) communications. Our architecture mainly pretends to enhance the performance of TCP handovers in 802.11 networks. VSPLIT includes a cross-layer TCP protocol, called VSPLIT-TCP, that adapts the congestion control during the handover, learning the new characteristics of the network after the handover using the mechanisms provided by the IEEE 802.21 Media Independent Handover (MIH) services. VSPLIT has been implemented and tested in the NS-3 simulator. We include the some of the most interesting performance evaluation results, which show a good performance of our proposal for the intended scenario.     

An efficient hybrid evolutionary algorithm for scheduling with setup times and weighted tardiness minimization

We confront the job shop scheduling problem with sequence-dependent setup times and weighted tardiness minimization. To solve this problem, we propose a hybrid metaheuristic that combines the intensification capability of tabu search with the diversification capability of a genetic algorithm which plays the role of long term memory for tabu search in the combined approach. We define and analyze a new neighborhood structure for this problem which is embedded in the tabu search algorithm. The efficiency of the proposed algorithm relies on some elements such as neighbors filtering and a proper balance between intensification and diversification of the search. We report results from an experimental study across conventional benchmarks, where we analyze our approach and demonstrate that it compares favorably to the state-of-the-art methods.     

The wise cursor: assisted selection in 3D serious games

In recent years, the evolution of 3D graphics hardware and software has lead to a growing interest for serious games in three-dimensional virtual environments for learning, training, and rehabilitation. Many of these games are based on a first-person-shooter paradigm in which users navigate through the environment, select, and manipulate virtual objects. The target users of these applications are not necessarily usual gamers, and they often have difficulties in navigating and interacting in the 3D environment. This paper proposes the wise cursor, a new method for selection that improves the usability and accessibility of mouse-driven serious games in 3D environments. At each user click, the proposed method computes a list of objects candidates to be selected and their probability of being the desired one. Depending on the uncertainty of the probability distribution, either one object is selected or a mechanism to clarify the selection is proposed. In the former case, if the selected object is within the user avatar’s scope, the action associated to it is realized, otherwise the application automatically navigates toward it. In this way, selection and navigation are eased. The empirical results of the usability tests show that this technique is fast, practical, and that it requires little user’s skills. Thus, it can make serious games usable for a wider range of users who can concentrate on the training objectives without technological barriers.