Tunable Guided‐Mode Resonance Grating Filter

The optical characteristics of shallow 2D nanostructured polycarbonate samples are presented. Tunable guided‐mode resonance filters are experimentally demonstrated for the visible spectral range when functional coatings are applied to 2D nanostructures by means of atomic layer deposition. The wavelength position of the reflection peaks can be easily tuned in a broad range (>150 nm) through rotation of the optical element around the axis normal to the substrate without changing the rest of the optical setup. Rigorous coupled wave approach simulation of model systems is performed to obtain insight into the complexity of the optical properties of these systems. The photonic nanostructures presented here are promising optics for application in ultra‐compact, portable, miniaturized optical systems.     

A methodology for large-scale R&D planning based on clusteranalysis

A decision-support approach to large-scale R&D planning is described. A quantitative model based on three analytical tools, the interaction matrix, hierarchical cluster analysis, and the Boston Consulting Group (GCG) strategic planning matrix, is used. Results of the model are used to determine the number of R&D program areas, the technological focus of each R&D program area, and the relative allocation of resources to the R&D program areas. Traditional optimization techniques for R&D planning often generate solutions without allowing for the judgement, experience, and insight of the decision maker. The decision-support approach presented supports, rather than replaces, the judgement of the R&D planner by using a graphic display of the relative position of technology clusters, and by using an interactive and iterative approach to problem solving. An application to R&D program planning for Virginia's Center for Innovative Technology's Commercial Space program is presented     

Co‐simulation‐based modeling and performance analysis of hybrid fiber–wireless links

We present a new approach for the performance analysis of hybrid fiber/wireless communication systems. This approach is based on a co‐simulation using two types of dedicated software: the first is used for RF/wireless systems whereas the second is devoted to optical communication systems. The proposed method enables simultaneous simulation of all elements of the radio‐over‐fiber link with accurate modeling. A low‐cost wireless local area network over a fiber distribution system is implemented in order to validate the results experimentally. Simulation results are in good agreement with experimental measurements in terms of EVM evolution for different link element configurations. Copyright © 2011 John Wiley & Sons, Ltd.     

Dynamic Origin–Destination Flow Estimation Using Cellular Communication System

This paper aims to develop a new approach for the estimation of dynamic origin–destination (O–D) flow using cell phones as traffic probes. The state-space model, which depends on the autoregressive dynamics of O–D flow and the time series for link volume counts, was adopted. Unlike a direct approach that uses sample O–D flows extracted from the cell-based location data as additional observations, an indirect approach is proposed wherein the assignment map in the model is derived from the passing time at observation locations and the path choice proportion. A probe phone's passing time at a certain point in a cell was approximated with its entry and exit times at cell boundaries. The average path choice proportion was also estimated using cell-based trajectories of probe phones. The simulation experiments confirmed that the approach was successfully applicable to the real-world freeway network. The results suggest that the O–D flows estimated from the present approach are promising in that the mean absolute error ratio was smaller than the case wherein only historical O–D flows are concerned. A sensitivity analysis revealed that the present approach met the requirements for an urban area encompassing a huge number of cell phone users in a microcell system.      

An interactive approach for selecting IR&D projects

The authors present a strategy for systematically allocating resources to competing independent research and development (IR&D) projects in a company building systems for the US Department of Defense. The approach is less mathematically complex than many techniques reported in the literature, utilizing the judgement of key business and technical elements in the organization. The authors first give a taxonomy characterizing various approaches and briefly review R&D selection methods reported in literature. Then they describe an interactive process that they have developed for selecting IR&D projects which, rather than substituting complex calculations for good technical and material judgement, facilitates better utilization of the expertise of various organizational elements within the context of corporate strategic planning. Procedures are included for idea submittal and evaluation. Experiences are discussed obtained during the application of the process to a corporation with multiple business units     

Nonlinear smoothing of <Emphasis Type="Italic">N</Emphasis>-dimensional data using successive over-relaxation method

Local smoothing of N-dimensional data can be performed in many ways. This paper is oriented to local penalization and its minimization which generates a system of nonlinear equations. This approach enables to realize trade-off between denoising, edge, and structure preserving. This is mainly useful in the case of discontinuous signals and images. Various penalization strategies can be used for this task, but only constrained penalizations (Tukey, Welsch, Andrews) are successful. Novel nonlinear method is inspired by successive over-relaxation scheme for linear systems of equations, but it is applied to nonlinear root-finding problem. The method is designed to be stable for several smoother types. Root bracketing inside inner loop is included in the procedure and extends the stability range in many applications. Numerical experiments are performed on 1D signal and 2D image. Optimum relaxation factors are found experimentally for maximum rate of convergence. The main results of experimental part are: preference of Tukey method in the case of discontinuous signal, similarity of proposed methods in the case of continuous signal, and efficiency of Tukey method followed by watershed transform in the case of image segmentation. Selected smoothers are recommended mainly for signals and images with discontinuities and can be useful in signal and image enhancement, analysis, segmentation, and classification.     

Performance analysis of single carrier and multicarrier DS‐CDMA systems over generalized fading channels

Using a recently developed moment generating function‐based approach for the performance evaluation of digital communications over fading channels, we present a unified approach for the exact performance analysis of binary direct‐sequence code division multiple access (DS‐CDMA) systems operating over generalized frequency‐selective fading channels. The results are applicable to single carrier systems employing RAKE reception as well as to multicarrier DS‐CDMA systems with frequency diversity. Aside from simplifying previous results both analytically and computationally, the proposed approach also gives a solution for many situations which heretofore defied a simple form. Copyright © 2001 John Wiley & Sons, Ltd.     

Some soft measures for performance analysis: The “core” dimensions of expert system quality

The post-implementation evaluation of new technologies such as artificial intelligence, multimedia or parallel computing systems which are in operation is a much neglected problem. There is a lack of methods, techniques and tools for the practitioner to analyze the performance such systems. In earlier work, we have presented a framework and methodology that described a socio-technical approach for evaluating expert systems. In short, we determined the features and characteristics of expert systems that are most critical for their “implementation success”. This was the result of empirical evidence from a first-ever field study of expert systems in production. In this paper, specifically tailored to an audience of generalists, we retrospectively put our work into the framework of performance measurement and analysis. The end-result of our investigations is that we have definitional clarity as to how we may alternately evaluate such decision support systems.     

Practical Profiles for Managing Systems Engineering R&D

A new and practical way of profiling R & D projects is presented. The operational context is the investment of discretionary R & D funds by systems engineering firms. In this work program positioning profile, R & D projects are identified as one of four types: targeting, reinforcing, enabling, or remodeling, according to the relationship between the R &D project and the systems engineering work program. A portfolio map is introduced to provide a visual representation of a set of R & D projects and to show likely transitions between project types over time. The new profile and portfolio map can support management efforts to characterize and assess an R & D portfolio for its contribution to ongoing systems engineering work. In addition to this new project profile, other profiling strategies are discussed in the framework of an R & D balanced scorecard. The multiple profiles are a natural consequence of the inherent performance multidimensionality of the R &D activity in the wide-ranging discipline and practice of systems engineering.     

Delay-Dependent Stability for Discrete 2D Switched Systems with State Delays in the Roesser Model

This paper is concerned with the problem of delay-dependent stability analysis for a class of two-dimensional (2D) discrete switched systems described by the Roesser model with state delays. First, the concept of average dwell time is extended to 2D switched systems with state delays. Then, based on the average dwell time approach, a delay-dependent sufficient condition for the exponential stability of the addressed systems is derived. All the results are formulated in terms of linear matrix inequalities (LMIs), which can be solved efficiently. A numerical example is given to illustrate the effectiveness of the proposed method.     

Reversible Formation of g‐C3N4 3D Hydrogels through Ionic Liquid Activation: Gelation Behavior and Room‐Temperature Gas‐Sensing Properties

Many unique properties arise when the 3D stacking of layered materials is disrupted, originating nanostructures. Stabilization, and further reorganization of these individual layers into complex 3D structures, can be essential to allow these properties to persist in macroscopic systems. It is demonstrated that a simple hydrothermal process, assisted by ionic liquids (ILs), can convert bulk g‐C₃N₄ into a stable hydrogel. The gelation occurs through delamination of the layered structure, driven by particular interactions between the IL and the carbon nitride sheets, forming an amphiphilic foam‐like network. This study employs spectroscopic and computational tools to unravel the gelation mechanism, and provides a rational approach toward the stabilization of 2D materials in hydrogels. The solution‐processable hydrogels can also be used as building blocks of complex devices. Chemiresistive gas sensors employing g‐C₃N₄ 3D hydrogels exhibit superior response at room temperature, enabling effective gas sensing under low power conditions.     

Efficient device‐to‐device discovery and access procedure for 5G cellular network

A large number of new data‐consuming applications are emerging, and many of them involve mobile users. In the next generation of wireless communication systems, device‐to‐device (D2D) communication is introduced as a new paradigm to offload the increasing traffic to the user equipment. Before the traffic transmission, D2D discovery and access procedure is the first important step which needs to be completed. In this paper, our goal is to design a device discovery and access scheme for the fifth generation cellular networks. We first present two types of device discovery and access procedures. Then we provide performance analysis based on the Markov process model. In addition, we present numerical simulation on the Vienna Matlab platform. The simulation results demonstrate the viability of the proposed scheme. Copyright © 2015 John Wiley & Sons, Ltd.     

LMI approach to stability of 2D positive systems

The asymptotic stability of positive 2D linear systems with delays (systems of order higher one) described by the Roesser model, the 2D Fornasini–Marchesini models and the general model is addressed. It is shown that the linear matrix inequalities (LMIs) can be used to checking the asymptotic stability of the positive 2D systems. Using LMI approach necessary and sufficient conditions for the asymptotic stability of the positive 2D systems with delays are established. The efficiency of the LMI approach is demonstrated on numerical examples of positive 2D linear systems with delays.

Chinese‐Noodle‐Inspired Muscle Myofiber Fabrication

Much effort has been made to engineer artificial fiber‐shaped cellular constructs that can be potentially used as muscle fibers or blood vessels. However, existing microfiber‐based approaches for culturing cells are still limited to 2D systems, compatible with a restricted number of polymers (e.g., alginate) and always lacking in situ mechanical stimulation. Here, a simple, facile, and high‐throughput technique is reported to fabricate 3D cell‐laden hydrogel microfibers (named hydrogel noodles), inspired by the fabrication approach for Chinese Hele noodle. A magnetically actuated and noncontact method to apply tensile stretch on hydrogel noodles has also been developed. With this method, it is found that cellular strain‐threshold and saturation behaviors in hydrogel noodles differ substantially from their 2D analogs, including proliferation, spreading, and alignment. Moreover, it is shown that these cell‐laden microfibers can induce muscle myofiber formation by tensile stretching alone. This easily adaptable platform holds great potential for the creation of functional tissue constructs and probing mechanobiology in three dimensions.     

Corporate R&D strategy portfolio in Japanese and Australiantechnology-based firms: an empirical study

This paper presents an empirical study on the strategic structure of corporate R&D in Japanese and Australian technology-based companies. The perceived importance and distribution of basic research, precompetitive strategic research and applied research within a corporate R&D portfolio are examined through a comparative analysis of survey data. The results suggest that Japanese firms tend to place great emphasis on basic and precompetitive strategic research, although applied research still retains its importance. They recognize that basic research is critical to achieve long-term competitive advantages in the marketplace. Australian firms also realize the importance of basic research and the use of portfolio approach in R&D management. However, research work in Australian firms tends to focus on applied research with only a limited involvement in medium- and long-term research. Finally, it is concluded that Japanese firms utilize a portfolio approach to corporate R&D management more systematically than do their Australian counterparts     

A Constructive Approach to Stabilizability and Stabilization of a Class of nD Systems

This paper presents a constructive approach to the problem of output feedback stabilizability and stabilization of a class of linear multidimensional (nD, n>2) systems, whose varieties of the ideals generated by the reduced minors are infinite with respect to not more than two variables. The main idea of the proposed approach is to decompose the variety of an nD system in this class into a union of several varieties, each of which is defined by polynomials in just two variables. The new method can be considered as a combination of Gröbner bases and existing results on two-dimensional (2D) digital filter stability tests and on stabilizability and stabilization of 2D systems. An example is illustrated.     

Analysis of outage probability for in‐band device‐to‐device communications underlaying cellular network

One of the key strategies for jointly increasing throughput and optimum resource allocation in 5G is device‐to‐device (D2D) communications, which can be obtained by minimizing the outage probability considered as an objective function of optimization problem. To minimize this objective function, we found that outage probability should be modeled by jointly considering the effect of interference, noise, and multipath phenomena. In this paper, the exact formulas for outage probability of in‐band D2D communications underlying cellular network are proposed. In the proposed model, additive white Gaussian noise and Rayleigh multipath fading are considered into 2 radio resource reuse scenarios. In the first scenario, each D2D pair is allowed to reuse radio resource block of one cellular user, whereas in the second scenario, 2 resources of 2 cellular users can be reused. The proposed formulas are compared to the approximate (nonexact) ones, which models additive white Gaussian noise by a constant variance. The numerical analysis for the first and second scenarios show that the approximate formulas and respected exact ones are in accordance with simulation results in MATLAB. Moreover, based on nonorthogonal multiple access approach, 2 approximations for the nonexact and the proposed formulas are extracted, which are acceptable for multiple resource reuse scenario. As a remarkable result, simulation results show that when the distance of the D2D pair from the respected cellular user is more than 71 m (2 times greater than average distance between the D2D nodes), multiple‐reuse scenarios offer higher throughput compared to 1‐reuse scenario in an acceptable outage probability.     

Variables influencing the performance of defense R&Dcontractors

Several variables affect the performance of contractors on defense research and development (R&D) contracts. These variables can be classified as endogenous or exogenous. Endogenous variables are influenced by the project manager and the contracting officer, while exogenous variables are not. The effects of four endogenous variables on contractor performance are examined. These variables are: type of R&D, type of solicitation, type of contract, and size of business of the contractor. Surveys were conducted in 1978 and 1986 on completed R&D contracts. The measurement factors used were technical performance, schedule, quality of reports/products, cost, and overall assessment. A two-way analysis of variance was used to examine how the endogenous variables influenced the contractor performance. The authors conclude that, except for size of business, all variables had an effect on some of the performance factors. The recommendations include a proposed new contracting approach for major development contracts. This approach is based upon life-cycle cost minimization, and it favors the use of cost contracts over fixed price in the later stages of development     

Energy efficiency comparison between distributed and co‐located MIMO systems

Energy efficiency (EE) is becoming more and more important in future wireless communications because of limited battery power in mobile terminals. In this paper, we compare EE of the distributed MIMO (D‐MIMO) and co‐located MIMO (C‐MIMO) in uplink systems. Taking into account both circuit and transmit power, we derive an analytical expression for EE of D‐MIMO and C‐MIMO systems in a composite Rayleigh‐lognormal channel. What is more, an optimization algorithm is proposed to get the optimal EE values while satisfying given spectral efficiency requirement for both D‐MIMO and C‐MIMO systems. Simulation results show that D‐MIMO systems are more energy effective than C‐MIMO systems when considering the realistic systems, and the optimal EE can be obtained by the proposed algorithm while satisfying given spectral efficiency requirement. Copyright © 2012 John Wiley & Sons, Ltd.     

Development of Platform-Based Knowledge Map Service to get Data Insights of R&amp;D Institution on User-Interested Subjects

Generally, any database is developed for the purpose of providing certain services for retrieval or management of data. If rules or processes designed to extract and analyze data in consideration of data characteristics are simplified and services are provided to users by visualizing analysis results in an easy-to-understand fashion, users will be able to get diverse insights easily without much cost or effort. If this kind of database is constructed and provided in NTIS database as well (e.g., project data, research outcome data such as paper and patent, personnel information, etc.) users might be able to get varied insights on national R&D data. The approach proposed in this study is significant in that it provides platform-based analysis services which can create a knowledge map after extracting and analyzing user-interested data and subsequently visualizing the results. Furthermore, this study is intended to make users obtain insight on a research institute more easily by providing analyzable additional information, not only as a list of research institutes in user-preferred subjects after providing the results of the analysis on R&D expenses, but also in regional distribution and annual changes in core research institutes, focusing on those taking part in national R&D programs in certain fields.