Projection Scheme Research Articles

Transmit Antenna Selection and Beamformer Design for Secure Spatial Modulation With Rough CSI of Eve

The security of spatial modulation (SM) aided networks can always be improved by reducing the desired link's power at the cost of degrading its bit error ratio performance and assuming the power consumed to artificial noise (AN) projection (ANP). We formulate the joint optimization problem of maximizing the secrecy rate (Max-SR) over the transmit antenna selection and ANP in the context of secure SM-aided networks, which is mathematically a non-linear mixed integer programming problem. In order to solve this problem, we provide a pair of solutions, namely joint and separate solutions. Specifically, an accurate approximation of the SR is used for reducing the computational complexity, and the optimal AN covariance matrix (ANCM) is found by convex optimization for any given active antenna group (AAG). Then, given a large set of AAGs, simulated annealing mechanism is invoked for optimizing the choice of AAG, where the corresponding ANCM is recomputed by this optimization method as well when the AAG changes. To further reduce the complexity of the above-mentioned joint optimization, a low-complexity two-stage separate optimization method is also proposed. Furthermore, when the number of transmit antennas tends to infinity, the Max-SR problem becomes equivalent to that of maximizing the ratio of the desired user's signal-to-interference-plus-noise ratio to the eavesdropper's. Thus our original problem reduces to a fractional programming problem, hence a significant computational complexity reduction can be achieved for the optimization problem. Our simulation results show that the proposed algorithms outperform the existing leakage-based null-space projection scheme in terms of the SR performance attained, and drastically reduces the complexity at a slight SR performance reduction.

A Factorization of Least-Squares Projection Schemes for Ill-Posed Problems

Abstract We give a factorization formula to least-squares projection schemes, from which new convergence conditions together with formulas estimating the rate of convergence can be derived. We prove that the convergence of the method (including the rate of convergence) can be completely determined by the principal angles between T † ⁢ T ⁢ ( X n ) {T^{\dagger}T(X_{n})} and T * ⁢ T ⁢ ( X n ) {T^{*}T(X_{n})} , and the principal angles between X n ∩ ( 𝒩 ⁢ ( T ) ∩ X n ) ⊥ {X_{n}\cap(\mathcal{N}(T)\cap X_{n})^{\perp}} and ( 𝒩 ⁢ ( T ) + X n ) ∩ 𝒩 ⁢ ( T ) ⊥ {(\mathcal{N}(T)+X_{n})\cap\mathcal{N}(T)^{\perp}} . At the end, we consider several specific cases and examples to further illustrate our theorems.

Relation-Aware Pedestrian Attribute Recognition with Graph Convolutional Networks

In this paper, we propose a new end-to-end network, named Joint Learning of Attribute and Contextual relations (JLAC), to solve the task of pedestrian attribute recognition. It includes two novel modules: Attribute Relation Module (ARM) and Contextual Relation Module (CRM). For ARM, we construct an attribute graph with attribute-specific features which are learned by the constrained losses, and further use Graph Convolutional Network (GCN) to explore the correlations among multiple attributes. For CRM, we first propose a graph projection scheme to project the 2-D feature map into a set of nodes from different image regions, and then employ GCN to explore the contextual relations among those regions. Since the relation information in the above two modules is correlated and complementary, we incorporate them into a unified framework to learn both together. Experiments on three benchmarks, including PA-100K, RAP, PETA attribute datasets, demonstrate the effectiveness of the proposed JLAC.

IFC Environmental & Social Performance Standards: Soft Law Project & Company Financing Partnerships towards Good Environmental Governance, Business Sustainability and Sustainable Development in Developing Countries

This study is an outcome of a previous work by the author captioned ‘Sustainable Development: A Soft Law Concept Transforming SD-Oriented Initiatives of the UN System into Hard Law Instruments in UN Member-states and Promoting Partnerships around the Globe’. The previous work establishes that there are numerous examples of SD-oriented partnership mechanisms associated with business sustainability, environmental protection, good public sector governance (good governance: GG) and sustainable development (SD), of which the Sustainability Framework of the International Finance Corporation (IFC) is one. The aim of this study is to examine how the IFC’s environmental and social (E&S) performance standards, as key aspects of the corporation’s sustainability framework, are being implemented as soft law mechanisms in developing countries (also called developing markets) and emerging economies (also known as emerging markets), where the IFC is engaged in financing, managing developmental projects and corporate financing in various ways. The sustainability framework and its component E&S standards are international benchmarked standards that have the potential to boost business sustainability and overall SD in developing markets and economies in transition. The study arrives at the finding that the IFC’s sustainability framework and the E&S standards ingrained in it are engineering the E&S performances of IFC clients engaged in IFC project and corporate financing schemes in developing countries and emerging economies, as well as contributing to business sustainability. These standards are also boosting environmental protection, good environmental governance, corporate social responsibility, social responsibility of host governments and generating SD-oriented partnerships, such as Private Sector Partnerships and Public-Private Sector Partnerships, which contribute to betterment of the welfare of citizens, generic human wellbeing and environmentally-sound and socio-economically equitable growth, prosperity and SD in developing countries. This is particularly so in developing countries where domestic environmental laws, corporate responsibility systems and government social responsibility fall short of the stipulations of the IFC’s sustainability framework and its component E&S performance standards. Keywords: International Finance Corporation (IFC); Sustainability Framework; Project Financing; Corporate Financing; Developing Countries; Emerging Markets; Environmental and Social Performance (E&S) Standards; Sustainability Framework; Soft Law; Business Sustainability; Sustainable Development; Good Environmental Governance (GEG); Government Social Responsibility (GSR); Corporate Social Responsibility (CSR); SD-oriented Partnerships; Private Sector Partnerships; Public-Private Sector Partnerships (PPSPs); Impact-benefits; Human Wellbeing. DOI: 10.7176/IAGS/81-07 Publication date: April 30 th 2020

Transient electrohydrodynamic flow with concentration-dependent fluid properties: Modelling and energy-stable numerical schemes

Transport of electrolytic solutions under influence of electric fields occurs in phenomena ranging from biology to geophysics. Here, we present a continuum model for single-phase electrohydrodynamic flow, which can be derived from fundamental thermodynamic principles. This results in a generalized Navier–Stokes–Poisson–Nernst–Planck system, where fluid properties such as density and permittivity depend on the ion concentration fields. We propose strategies for constructing numerical schemes for this set of equations, where the electrochemical and the hydrodynamic subproblems are decoupled at each time step. We provide time discretizations of the model that suffice to satisfy the same energy dissipation law as the continuous model. In particular, we propose both linear and non-linear discretizations of the electrochemical subproblem, along with a projection scheme for the fluid flow. The efficiency of the approach is demonstrated by numerical simulations using several of the proposed schemes.

Relative Topological Entropy for Actions of Non-discrete Groups on Compact Spaces in the Context of Cut and Project Schemes

In the study of aperiodic order via dynamical methods, topological entropy is an important concept. In this paper, parts of the theory, like Bowen’s formula for fibre wise entropy or the independence of the definition from the choice of a Van Hove sequence, are extended to actions of several non-discrete groups. To establish these results, we will show that the Ornstein–Weiss lemma is valid for all considered groups which appear in the study of cut and project schemes.

Enhancing pedestrian mobility in Smart Cities using Big Data

Smart City is an emerging concept in global urban development. A Smart City applies ICT technologies to provide greater efficiencies for its urban areas and civilian population. One of the key requirements for a Smart City is to exploit data from its ICT infrastructure (such as Internet of Things connected sensors) to improve city services and features such as accessibility and sustainability. To address this requirement, the City of Melbourne (COM) Smart City office maintains several hundred data sets relating to urban activity and development. These datasets address parking, mobility, land use, 3D data, statistics, environment, and major city developments such as rail projects. One promising dataset relates to pedestrian traffic. Data are obtained from sensors and updated on the COM website (City of Melbourne Open Data Platform: https://data.melbourne.vic.gov.au/.) at regular intervals. These data include the number of pedestrians passing 53 specific locations in the central business district and also their times and directions of travel. In a 24 h period, over 650,000 pedestrians were counted passing all locations. Peak rates of several thousand pedestrians per minute are regularly recorded during city rush hours at hotspots making the data amenable to Big Data analysis techniques. Results are obtained in graphical format as heatmaps and charts of city pedestrian traffic using both Microsoft Excel® for static analysis and PowerBI® for more advanced interactive visualisation and analysis. These findings can identify pedestrian hotspots and inform future locations of traffic lights and street configurations to make the city more pedestrian friendly. Further, the experience gained can be used to examine other data sets such as bicycle traffic that can be analysed to inform city infrastructure projects. Future work is suggested that could link these pedestrian flow data with social media data from smartphones and potentially wearable devices such as fitness monitors to correlate pedestrian satisfaction with traffic flow. The ‘happiness’ effect of pedestrians passing through green areas such as city parks can also be quantified. This research was undertaken with the assistance of Swinburne University under its Capstone Project scheme.

Stress-based topology optimization of compliant mechanisms design using geometrical and material nonlinearities

In this work, a density-based method is applied for synthesizing compliant mechanisms using topology optimization. This kind of mechanisms uses the elastic strain as the basis for kinematic actuation and it is widely used in precision mechanical devices, in biomedical engineering, and recently in MicroElectroMechanical Systems (MEMS). Geometrical and material (compressible hyperelasticity) nonlinearities are taken into account to obtain mechanisms near real-world applications. A strength criterion for the optimization problem is applied, to design compliant mechanisms that fulfill the desired kinematic tasks while complying with a stress threshold. The addition of a stress constraint to the formulation also aims to alleviate the appearance of hinges in the optimized design. Employing benchmark examples, we investigate the influence of a nonlinear formulation with a stress constraint in the final designs. It is shown that material nonlinearity plays an important role for stress constraint problems. The use of a projection scheme helps to obtain optimized topologies with a high level of discreteness. The Method of Moving Asymptotes (MMA) is applied for design variables updating and the required derivatives are calculated analytically by the adjoint method.

An unstructured finite element model for incompressible two‐phase flow based on a monolithic conservative level set method

SummaryWe present a robust numerical method for solving incompressible, immiscible two‐phase flows. The method extends both a monolithic phase conservative level set method with embedded redistancing and a semi‐implicit high‐order projection scheme for variable‐density flows. The level set method can be initialized conveniently via a simple phase indicator field instead of a signed distance function (SDF). To process the indicator field into a SDF, we propose a new partial differential equation‐based redistancing method. We also improve the monolithic level set scheme to provide more accuracy and robustness in full two‐phase flow simulations. Specifically, we perform an extra step to ensure convergence to the signed distance level set function and simplify other aspects of the original scheme. Lastly, we introduce consistent artificial viscosity to stabilize the momentum equations in the context of the projection scheme. This stabilization is algebraic, has no tunable parameters and is suitable for unstructured meshes and arbitrary refinement levels. The overall methodology includes few numerical tuning parameters; however, for the wide range of problems that we solve, we identify only one parameter that strongly affects performance of the computational model and provide a value that provides accurate results across all the benchmarks presented. This methodology results in a robust, accurate, and efficient two‐phase flow model, which is mass‐ and volume‐conserving on unstructured meshes and has low user input requirements, making it attractive for real‐world applications.

Finite-dimensional differential graded algebras and their geometric realizations

We prove that for any finite-dimensional differential graded algebra with separable semisimple part the category of perfect modules is equivalent to a full subcategory of the category of perfect complexes on a smooth projective scheme with a full separable semi-exceptional collection. Moreover, we also show that it gives a characterization of such categories assuming that a subcategory is idempotent complete and has a classical generator.

On degenerate sections of vector bundles

We consider the locus of sections of a vector bundle on a projective scheme that vanish in higher dimension than expected. We will find the largest components of this locus asymptotically, after applying a high enough twist to the vector bundle. We will also give an interpretation in terms of a limit in the Grothendieck ring of varieties.

Long-Term Impact of China’s Returning Farmland to Forest Program on Rural Economic Development

The Returning Farmland to Forest Program (RFFP) is widely known as one of China’s largest and most successful payment schemes for ecosystem service projects for the achievement of both environmental and economic sustainability. By sponsoring afforestation activities and compensating farmers for converting cropland to forest, the project was designed to achieve multiple goals. Ecologically, the program aims to expand forest cover and to reduce flood and soil erosion. Economically, it aims to alleviate poverty and improve rural livelihoods. Although the official metrics indicate successful program outcomes in the short term, researchers have reported mixed and controversial results for long-term outcomes. We combined the difference-in-difference (DID) with instrumental variables (IVs) regression to examine the long-term effects of China’s RFFP on local economic development. We found that (1) the RFFP has had a remarkably positive impact on local economic growth in the primary sector, but considerably limits the growth of enterprises above a designated size by 16.8%; (2) the RFFP is unable to promote the development of the secondary industry because it cannot effectively promote the transfer of rural laborers to the secondary industry sector; and (3) in addition to increasing the general budgetary expenditure of local finance by 7.50%, this program has significantly reduced local fiscal revenue by 35.50%. We suggest that eco-compensation should consider the performance of the RFFP in its evaluation criteria.

A fully decoupled, linear and unconditionally energy stable numerical scheme for a melt-convective phase-field dendritic solidification model

We consider in this paper numerical approximations of a melt-convective phase-field dendritic solidification model. A challenging numerical issue for solving this model is how to develop efficient time marching schemes that are not only unconditionally energy stable, but also linear and totally decoupled since the model is a highly coupled nonlinear system. We solve this issue by combining the modified projection scheme for the Navier–Stokes equations, the stabilized-Invariant Energy Quadratization method for the anisotropic phase field equation. Meanwhile, in order to obtain the fully decoupled feature, we introduce an auxiliary intermediate temperature variable to decouple the computation of the temperature from the phase field variable. We prove the unconditional energy stability of the developed scheme and further present various numerical simulations in 2D and 3D to demonstrate the accuracy and stability of the developed scheme.

A conservative SPH scheme using exact projection with semi-analytical boundary method for free-surface flows

This paper presents a novel SPH scheme for modelling incompressible and divergence-free flow with a free surface (IDFSPH) associated with semi-analytical wall boundary conditions. In line with the projection method, the velocity field is decoupled from the pressure field in the momentum equation. A Poisson equation, serving as the pressure solver, is obtained by which pressure field is decoupled completely from the velocity field. In particular, an exact projection scheme is deployed to fulfil the requirement of the divergence-free velocity field. The condition of incompressibility is satisfied by iteratively updating the density field till the convergence. The two-equation k–ε model is employed to describe the turbulence effects in Newtonian flows. It is shown that the discretised SPH schemes have the feature of both linear and angular momentum conservations. The semi-analytical wall method implements the appropriate integrals to evaluate the boundary contributions to the mass and momentum equations. In comparison to the boundary particle methods, it can greatly enhance the feasibility and efficiency with the complex geometries. The algorithm presented within this paper is applied to several academic test cases for which either analytical results or simulations with other methods are available. The comparisons verify that this scheme is provided with convincing efficiency and extensive applicability.

Experimental phase diagram, thermodynamic modeling and solidified microstructure in the Mo–Ni–W ternary system

In this work, the isothermal section at 900 °C, a liquidus projection and invariant reaction temperatures in the Mo–Ni–W ternary system were established using X-ray diffraction (XRD), Differential Scanning calorimeter (DSC) and electron probe micro-analysis (EPMA). Based on the experimental phase diagram data from the present work and the literature, the Mo–Ni–W system was assessed by means of the CALPHAD (CALculation of PHAse Diagrams) method. The liquid, fcc-(Ni), bcc-(Mo) and bcc-(W) phases were described with a regular solution model. The sub-lattice models were used to express Gibbs energies of the intermediate phases of MoNi3, MoNi, (Mo, W)Ni4, WNi and W2Ni. The present modeling covers the entire composition and an extensive temperature ranges of the Mo–Ni–W ternary system, and a set of self-consistent thermodynamic parameters were finally obtained. Comprehensive comparisons between the calculated and measured phase diagram data show that most experimental information is satisfactorily accounted for by the present thermodynamic description. Scheil solidification simulations for a few representative as-cast alloys were performed. It was found that the solidified microstructures can be reasonably described by the Scheil simulation. The liquidus projection and reaction scheme of the Mo–Ni–W system were generated by the presented modeling.

Comparison of Effective Exchange Integrals of H-H and H-He-H Chains vs. Single Molecules: A Theoretical Study

The effect of periodic structure on the effective exchange integral (Jab) was investigated using density functional theory calculations with plane-wave basis and approximate spin projection scheme ...

Projection Based Large Scale High-Dimensional Data Similarity Join Using MapReduce Framework

Similarity join has been widely used in many data analysis and data mining applications, we mainly focus on the scalability and performance problem of similarity join query on massive high-dimensional data set. p-stable distribution based projection scheme can implement dimension reduction effectively. Three novel approaches based on projection scheme are proposed to deal with massive high-dimensional data similarity join problem: Single projection method, Multiple projection method and Projection space partitioning method. Comprehensive experimental tests were performed to evaluate the performance of the above approaches. The experimental results show that the proposed approaches in this paper have good performance and scalability.

Application of Computer Simulation Method in Deep Underground Engineering of Complicated Geological Condition

Computer simulation technology is used to solve various engineering problems in the new century, particularly exemplified by the widespread use of numerical simulation research methods. Due to the complicated geological environment, a mine tunnel with a depth of 850 m in Hebei Province has caused various problems, such as large displacements and difficulty in implementing support schemes. However, the complex geological conditions make the project unique, and support schemes for other projects cannot be simply copied. In addition, due to engineering cost requirements, repeatedly evaluating different on-site support schemes is unacceptable. Therefore, it is necessary to obtain an appropriate support scheme through computer simulation technology. Consequently, by implementing FLAC3D software and using the progressive design method (PDM), a variety of support schemes are designed, and simulation tests, such as analysis and optimization of parameters, are performed. The research results show that through the analysis of stress, displacement and other aspects of the various schemes designed by using PDM, the finally selected scheme that was applied to the actual project achieved good results. The findings have proven the feasibility of the method, and the method can guide engineering problems under similar geological conditions.

Analysis and Evaluation of Structural Safety Inspection of a Railway Station

Based on the structural safety inspection of a railway station, first the current status and damage of the housing structure are introduced. It is analysed in this paper the safe capability of the railway station via precise on-site testing work. It is further discussed the influence of different modeling methods on the calculative results of the compressive bearing capacity of buttress column used in this masory structure. There is no software could accurately simulate the compressive bearing capacity of buttress column, for it is difficult to meet the actual needs of the project. This paper could be valuable future reference for the safety inspection and strengthening scheme of similar projects.

CATEGORICAL COMPLEXITY

We introduce a notion of complexity of diagrams (and, in particular, of objects and morphisms) in an arbitrary category, as well as a notion of complexity of functors between categories equipped with complexity functions. We discuss several examples of this new definition in categories of wide common interest such as finite sets, Boolean functions, topological spaces, vector spaces, semilinear and semialgebraic sets, graded algebras, affine and projective varieties and schemes, and modules over polynomial rings. We show that on one hand categorical complexity recovers in several settings classical notions of nonuniform computational complexity (such as circuit complexity), while on the other hand it has features that make it mathematically more natural. We also postulate that studying functor complexity is the categorical analog of classical questions in complexity theory about separating different complexity classes.