Unified Analytical Framework Research Articles

Fisher's hypothesis in time-frequency space: a premier using South Africa as a case study.

Fisher hypothesis is universally accepted as an integral portion of monetary theory and practice, and yet the empirical evidence confirming a full Fisher effect remains scarce and the relationship has been challenged on several theoretical grounds referred to as ‘puzzles’. Our paper suggests the use of continuous wavelet transforms as a unified analytical framework for confronting the different Fisher puzzles in a harmonious way. Taking South Africa as a case study, we focus on the inflation targeting period of 2002:01–2021:02 and use signal-image conversion tools such as wavelet power spectrum, wavelet coherence spectrum and phase-difference dynamics to extract signal features of nominal interest rates and inflation expectations and further explore their dynamic synchronization across a time–frequency plane/domain. Three unique findings emerge from our study. Firstly, across a time domain a full Fisher effect only holds in the pre-financial crisis period. Secondly, across the frequency spectrums, higher frequency oscillations gradually lose relevance to lower frequency oscillations providing evidence of volatility transfer in the Fisher effect. Lastly, the phase-dynamics indicate a consistent positive synchronization throughout the sample period which is line with the traditional Fisher effect. Overall, these findings highlight the success of the South African Reserve Bank in using inflation targeting to steer the expectations of economic agents under the tenures of the last three governors and provide important lessons for other Central banks.

Random-effects meta-analysis of effect sizes as a unified framework for gene set analysis.

Gene set analysis (GSA) remains a common step in genome-scale studies because it can reveal insights that are not apparent from results obtained for individual genes. Many different computational tools are applied for GSA, which may be sensitive to different types of signals; however, most methods implicitly test whether there are differences in the distribution of the effect of some experimental condition between genes in gene sets of interest. We have developed a unifying framework for GSA that first fits effect size distributions, and then tests for differences in these distributions between gene sets. These differences can be in the proportions of genes that are perturbed or in the sign or size of the effects. Inspired by statistical meta-analysis, we take into account the uncertainty in effect size estimates by reducing the influence of genes with greater uncertainty on the estimation of distribution parameters. We demonstrate, using simulation and by application to real data, that this approach provides significant gains in performance over existing methods. Furthermore, the statistical tests carried out are defined in terms of effect sizes, rather than the results of prior statistical tests measuring these changes, which leads to improved interpretability and greater robustness to variation in sample sizes.

Revealing the impact of a water-economy nexus-based joint tax management policy on the environ-economic system: An advanced exploration of double dividend strategies and multi-scale response mechanisms

Economic growth is constrained by water scarcity, and a unified policy analysis framework is required to enhance the coordinated development of the environ-economic system from the perspective of wastewater management. Thus, a multi-scale water-economic double dividend mechanism model (MWED) is first developed to (i) derive strategies for simultaneously achieving water scarcity mitigation and economic increase through compounding wastewater tax (WT) policies and reduced value-added tax (RVT) policies; (ii) explore the internal response mechanisms at the sectoral scale in the central region; and (iii) reveal the responses of economic output and multiple water resources in external regions under the cascading effects. This integrated approach of a computable general equilibrium model, an ecological network analysis, and a multi-regional input-output analysis is applied to Shanxi Province, China, a representative water-scarce region. The double dividend strategies of WT_6 yuan/ton*RVT_2%, WT_8 yuan/ton*RVT_2.5%, and WT_10 yuan/ton*RVT_3% were conducive to alleviating water scarcity and stimulating economic growth by adjusting the production structures or upgrading treatment technologies to reduce wastewater discharge, reducing the use of water-intensive energy sources to condense direct water consumption, and enhancing the connection between low water consumption sectors and advantageous economic sectors to optimize the virtual water network structure. Based on complex inter-regional relationships, these cascading effects can stimulate the economic output of other provinces and alleviate prevailing water scarcities by increasing virtual water inflows in economically developed regions and decreasing direct water consumption in economically undeveloped regions. The ability of water-rich regions to reconcile differences in water resource endowments can be further strengthened.

DLMP-Based Quantification and Analysis Method of Operational Flexibility in Flexible Distribution Networks

With high penetration of flexible resources, operational flexibility of flexible distribution networks (FDNs) is important to ensure high-quality electricity services. This paper proposes a value quantification and analysis method for operational flexibility in FDNs based on distribution locational marginal pricing (DLMP). First, flexibility constraints are formulated from the perspective of node integration, branch transfer, and network aggregation of flexibility. Then, a unified analytical framework for quantifying the operational flexibility is established, in which spatial-temporal transfer of flexibility is modeled with the derivation of flexibility sensitivity factors. Further, a DLMP-based flexibility value quantification model is proposed with nodal net power as the unit for flexibility pricing. The obtained flexibility price can not only quantify flexibility value but also be used to guide the flexible resources. Finally, the effectiveness of the proposed method is validated on a modified IEEE 33-node distribution system and a modified IEEE 123-node distribution system. Results verify that the proposed method can quantify the impact of nodal net power on operational flexibility and effectively improve the overall flexibility performance through the guide of flexibility price.

When Aloha and CSMA Coexist: Modeling, Fairness, and Throughput Optimization

With the emerging unlicensed spectrum sharing and Machine-to-Machine communications, the coexistence performance of multiple devices with different access schemes operating at the same unlicensed bands has received significant research interests. As the two most representative random-access schemes, Aloha and Carrier Sense Multiple Access (CSMA) both found wide applications in unlicensed bands. Yet most of the studies have focused on the coexistence of CSMA-based networks, leaving the coexistence of Aloha-based and CSMA-based networks largely unexplored. The challenge originates from the lack of a coexistence model of slotted Aloha and CSMA. In this paper, the throughput performance of coexisting Aloha and CSMA networks is characterized and optimized by extending a unified analytical framework proposed for random-access networks. The analysis shows that different from the single-network case where the maximum throughput of CSMA is much higher thanks to carrier sensing, when Aloha and CSMA coexist, Aloha would significantly outperform CSMA if each network optimizes its own throughput performance without cooperation, leading to poor throughput performance for CSMA and severe unfairness. To achieve fair coexistence, inter-network cooperation is crucial. The optimal transmission probabilities of Aloha and CSMA for maximizing the total network throughput under a given throughput ratio are further derived, and applied to coexisting LTE Unlicensed and WiFi networks to optimize their coexistence performance.

Communication Systems With Amplitude Detection: An Asymptotic Approach

Amplitude detection (AD) is a low-complexity nonlinear scheme for information retrieval, as it only considers the envelope of the received signal. This makes it ideal in applications with low-cost low-power devices such as the Internet of Things (IoT). We consider a basic Point-to-Point (P2P) setup and develop a unified analytical framework for the asymptotic symbol error rate (SER) performance of the maximum-likelihood (ML) decoder with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$M$ </tex-math></inline-formula> -ary amplitude-shift keying (ASK). The developed framework is general and can be applied for a large class of fading channels. The SER can be characterized by two parameters: the diversity order and the coding gain at a sufficiently high signal-to-noise regime. We derive closed-form expressions for the exact diversity order along with a lower and upper bound on the coding gain. We show that the diversity order is equal to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$m$ </tex-math></inline-formula> for Nakagami- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$m$ </tex-math></inline-formula> fading, whereas for the other considered models, it is equal to one. We also prove that among all possible binary modulations with equal power, the modulation with one symbol equal to zero [i.e., on–off keying (OOK)] achieves the minimum asymptotic SER. The mathematical framework developed for the P2P setup is extended for cooperative relay networks. Specifically, we consider a basic amplify-and-forward (AF) three-node relay topology that employs AD at both the relay and the destination. We analytically derive the ML decoder and study asymptotic bounds on the SER by showing that the proposed AF-AD relay setup can be transformed into an equivalent P2P-AD with respect to the ML decoder.

STAR-RIS Aided NOMA in Multicell Networks: A General Analytical Framework With Gamma Distributed Channel Modeling

The simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) is capable of providing full-space coverage of smart radio environments. This work investigates STAR-RIS aided downlink non-orthogonal multiple access (NOMA) multi-cell networks, where the energy of incident signals at STAR-RISs is split into two portions for transmitting and reflecting. We first propose a fitting method to model the distribution of composite small-scale fading power as the tractable Gamma distribution. Then, a unified analytical framework based on stochastic geometry is provided to capture the random locations of RIS-RISs, base stations (BSs), and user equipments (UEs). Based on this framework, we derive the coverage probability and ergodic rate of both the typical UE and the connected UE. In particular, we obtain closed-form expressions of the coverage probability in interference-limited scenarios. We also deduce theoretical expressions in conventional RIS aided networks for comparison. The analytical results show that optimal energy splitting coefficients of STAR-RISs exist to simultaneously maximize the system coverage and ergodic rate. The numerical results demonstrate that: 1) STAR-RISs are able to meet different demands of UEs located on different sides; 2) STAR-RISs with appropriate energy splitting coefficients outperform conventional RISs in the coverage and the rate performance.

Economic growth, industrial structure upgrading and environmental pollution: evidence from China

PurposeThe purpose of this study is to explore the impact of environmental pollution and industrial structure upgrading on environmental pollution in different stages based on the temporal and spatial heterogeneity of economic development level and industrial structure upgrading level in eastern, central and western regions of China and discuss whether there is adjustment effect and threshold effect in the process of economic growth affecting environmental pollution, and finally realizes sustainable economic development.Design/methodology/approachBased on panel data from 30 provincial-level administrative regions of China (excluding Tibet and Hong Kong, Macao and Taiwan) from 2000 to 2019, this paper uses the environmental Kuznets curve, regulating effect model and panel threshold model to analyze the impact of economic growth and industrial structure upgrading on environmental pollution.FindingsThe results present that the uneven distribution of natural resources leads to different levels of economic development and industrial structure upgrading in eastern and western regions, and its impact on environmental pollution is also different. Economic growth and industrial structure upgrading have a positive effect on environmental pollution, and the relationship between economic growth and environmental pollution is inverted U-shaped. At present, the eastern, central and western regions of China are at the right end of the inverted U-shaped relationship. In general, industrial structure upgrading in eastern, central and western regions has a significant inhibitory effect on environmental pollution. Industrial structure upgrading has a negative moderating effect on the relationship between economic growth and environmental pollution, and the regulating effect is most significant in the central region, followed by the eastern region, and not significant in the western region. The results of panel threshold model show that the industrial structure upgrading can slow down the positive impact of economic growth on environmental pollution and strengthen the negative moderating effect of industrial structure upgrading on economic growth and environmental pollution.Originality/valueThe innovation of this study is to bring economic growth, industrial structure upgrading and environmental pollution into a unified analytical framework, analyze the impact of economic development and industrial structure upgrading levels in different periods on environmental pollution, and select industrial structure upgrading as the moderating variable and threshold variable. It provides a thought for the influence mechanism of different levels of industrial structure upgrading on economic growth and environmental pollution. Based on the panel data in China, this study emphasizes the concept of sustainable development, adheres to green development and proposes relevant policies to improve environmental pollution. And this paper proposes relevant policies to improve environmental pollution from the perspective of transforming economic growth mode and optimizing industrial structure in China, which also has reference significance for developing countries to realize sustainable economic development.

Static and dynamic eigenvalues in unified stability studies

A framework for unified analysis of small-signal and large-signal power system stability based on static and dynamic eigenvalues is proposed in this paper. The presented implementation is based on Gear's method, which is a two-step integration method for numerical simulation with self-adaptive time-step. Furthermore, it can be easily configured for providing the state matrix as basis for calculating the system eigenvalues during simulation. Thus, the presented framework allows for eigenvalue-based analysis of small-signal dynamics and stability margin at any steady-state operating point during a time-domain simulation. Furthermore, Linear Time-Varying system theory is utilized for modal analysis during large-signal transients. For this purpose, dynamic eigenvalues and eigenvectors are calculated by solving a Riccati equation to generalize the modal analysis during transient conditions. The stability is evaluated by calculating the Lyapunov exponent of the mode-vector of the system. The results from numerical analysis of three case studies are presented to evaluate and illustrate the characteristics of the presented approach for unified small-signal and transient stability analysis.

Non-Overlapping Domain Decomposition via BURA Preconditioning of the Schur Complement

A new class of high-performance preconditioned iterative solution methods for large-scale finite element method (FEM) elliptic systems is proposed and analyzed. The non-overlapping domain decomposition (DD) naturally introduces coupling operator at the interface γ. In general, γ is a manifold of lower dimensions. At the operator level, a key property is that the energy norm associated with the Steklov-Poincaré operator is spectrally equivalent to the Sobolev norm of index 1/2. We define the new multiplicative non-overlapping DD preconditioner by approximating the Schur complement using the best uniform rational approximation (BURA) of Lγ1/2. Here, Lγ1/2 denotes the discrete Laplacian over the interface γ. The goal of the paper is to develop a unified framework for analysis of the new class of preconditioned iterative methods. As a final result, we prove that the BURA-based non-overlapping DD preconditioner has optimal computational complexity O(n), where n is the number of unknowns (degrees of freedom) of the FEM linear system. All theoretical estimates are robust, with respect to the geometry of the interface γ. Results of systematic numerical experiments are given at the end to illustrate the convergence properties of the new method, as well as the choice of the involved parameters.

Challenges and opportunities for using natural history collections to estimate insect population trends.

Natural history collections (NHC) provide a wealth of information that can be used to understand the impacts of global change on biodiversity. As such, there is growing interest in using NHC data to estimate changes in species' distributions and abundance trends over historic time horizons when contemporary survey data are limited or unavailable. However, museum specimens were not collected with the purpose of estimating population trends and thus can exhibit spatiotemporal and collector-specific biases that can impose severe limitations to using NHC data for evaluating population trajectories. Here we review the challenges associated with using museum records to track long-term insect population trends, including spatiotemporal biases in sampling effort and sparse temporal coverage within and across years. We highlight recent methodological advancements that aim to overcome these challenges and discuss emerging research opportunities. Specifically, we examine the potential of integrating museum records and other contemporary data sources (e.g. collected via structured, designed surveys and opportunistic citizen science programs) in a unified analytical framework that accounts for the sampling biases associated with each data source. The emerging field of integrated modelling provides a promising framework for leveraging the wealth of collections data to accurately estimate long-term trends of insect populations and identify cases where that is not possible using existing data sources.

Mittag-Leffler synchronization of fractional-order coupled neural networks with mixed delays

This paper is devoted to investigating Mittag-Leffler synchronization of fractional-order coupled neural networks (FOCNNs) with mixed delays, where the time-varying delays and infinite distributed delays are both taken into account. Firstly, a universal delayed FOCNNs model is introduced, which includes several FOCNNs with various time delays structures such as distributed delays and constant delays or time-varying delays, as its special cases. Besides, for the case where the existing results cannot be applied to infinite time delays, a generalized fractional-order Halanay inequality is proposed, which facilitates the analysis of synchronization of FOCNNs. Based on the generalized inequality, a unified synchronization analysis framework for FOCNNs is established, which is also applied to the cases with commonly considered FOCNNs with distribute delays, constant or time-varying delays. All the derived synchronization criteria have similar results and can be easily verified. Finally, a numerical example is provided to show the effectiveness of obtained results.

A Tb/s Indoor MIMO Optical Wireless Backhaul System Using VCSEL Arrays

In this paper, the design of a multiple-input multiple-output (MIMO) optical wireless communication (OWC) link based on vertical cavity surface emitting laser (VCSEL) arrays is systematically carried out with the aim to support data rates in excess of 1 Tb/s for the backhaul of sixth generation (6G) indoor wireless networks. The proposed design combines direct current optical orthogonal frequency division multiplexing (DCO-OFDM) and a spatial multiplexing MIMO architecture. For such an ultra-high-speed line-of-sight (LOS) OWC link with low divergence laser beams, maintaining alignment is of high importance. In this paper, two types of misalignment error between the transmitter and receiver are distinguished, namely, radial displacement error and orientation angle error, and they are thoroughly modeled in a unified analytical framework assuming Gaussian laser beams, resulting in a generalized misalignment model (GMM). The derived GMM is then extended to MIMO arrays and the performance of the MIMO-OFDM OWC system is analyzed in terms of the aggregate data rate. Novel insights are provided into the system performance based on computer simulations by studying various influential factors such as beam waist, array configuration and different misalignment errors, which can be used as guidelines for designing short range Tb/s MIMO OWC systems.

Priority setting in early childhood development: an analytical framework for economic evaluation of interventions

BackgroundEarly childhood development (ECD) sets the foundation for healthy and successful lives with important ramifications for education, labour market outcomes and other domains of well-being. Even though a large number...

Finite capacity single-server queue with Poisson input, general service and delayed renovation

This paper is devoted to the performance evaluation of the finite–capacity single-server queue with Poisson input and general service times, which is equipped with the novel queue-control mechanism — called renovation with delay. Renovation implies that each customer, when leaving the system upon its service completion, may also remove customers waiting in the queue. The number of customers to be removed is selected each time independently of the previous decisions and probabilistically based on the given probability distribution. The renovation with the delay considered in this paper means that the system must accumulate the (known) fixed number of service completions before the next renovation can be triggered. First in the literature numerical evidence is given, that the long-run performance of the system with such delayed renovation mechanism can be similar to that of the systems with the well-known active queue management mechanisms such as random early detection, at least in its basic version. The key stationary performance characteristics reported are the loss probability and the mean number of customers in the system. The unified analytical framework for the computation of the key performance characteristics, which is of independent interest, is also developed.

The Hughes-Ryan Amendment and Intelligence Oversight: An Inflection Point in an Oppositional Relationship

ABSTRACT The Hughes-Ryan Amendment provided the foundation of modern intelligence oversight. It firmly established executive ownership of covert action, challenging the concept of internal plausible deniability. Moreover, it shifted the relationship between the executive and legislative branches in terms of intelligence, allowing Congress a toehold on what had been considered an almost purely executive branch function. While Hughes-Ryan’s importance is indisputable, its roots and catalyst have seldom been explored in detail. This article describes the political context of the Hughes-Ryan amendment, discusses how and why it was introduced and passed when it was, and explains the outcome of this legislation. It introduces a unique analytical framework to explain this process, exploring the dynamics of congressional behavior and institutional constraints to explain why the change that occurred, while definitive and impactful in the intelligence world, was limited in scope.

RIS-Assisted SSK Modulation: Reflection Phase Modulation and Performance Analysis

In this letter, we present a reconfigurable intelligent surface (RIS)-assisted space shift keying (SSK) modulation and reflection phase modulation (RPM) scheme, where RIS embeds its own information in the reflection phase shift of the reflected radio frequency (RF) signal. More specifically, the RIS simultaneously performs two tasks: i) reflecting the impinging RF signal with a discrete phase shift and ii) embedding the information bits in the phase shift. We perform joint detection for the RPM and SSK symbols using a maximum likelihood detector, and a unified analytical framework is presented for theoretical analysis of the average bit error rate (ABER) and ergodic capacity of the proposed scheme. All numerical results are thoroughly verified through Monte Carlo simulation. Numerical results reveal that the proposed scheme outperforms the conventional SSK scheme.

Performance Analysis of Dual-Hop RF/FSO Relaying Systems With Imperfect CSI

This paper proposes a unified performance analysis framework of asymmetric dual-hop radio-frequency/free-space optical (RF/FSO) transmission systems. The generalized independent and identically distributed (i.i.d.) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\alpha -\mu$</tex-math></inline-formula> distribution is considered for each branch in the RF link, whereas the FSO link is assumed to experience Málaga ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathcal {M}$</tex-math></inline-formula> ) fading with pointing error impairments. With amplify-and-forward (AF) and decode-and-forward (DF) relaying, the imperfect channel state information (CSI) of both links is considered. For the considered system, we first derive exact and novel analytical expressions for the probability density function (PDF) and cumulative distribution function (CDF) of the end-to-end signal-to-noise ratio (SNR). Furthermore, we obtain key performance metrics such as outage probability (OP), average bit-error-rate (ABER), and effective capacity (EC). The important effects of channel parameters on the system are disclosed from mathematical analysis and are further validated by Monte-Carlo simulations.

A Unified Analytical Framework for RSS-Based Localization Systems

A Unified Analytical Framework for RSS-Based Localization Systems

Distortions of National Policies to Renewable Energy Cooperation Mechanisms

The EU endeavors to stimulate the use of renewable energy cooperation mechanisms. These cooperation mechanisms can significantly reduce the policy cost for meeting renewable targets. Several authors, however, have raised concerns that such cooperation mechanisms can be subject to efficiency losses due to different national regulatory conditions, and due to an ill-advised selection of cross-border support instruments. A quantitative evaluation of these effects remains missing. To address this gap, we first introduce a unifying analytical framework to show how optimal cross-border renewable energy trade should be organized and how these mechanisms could be distorted. We then develop a partial equilibrium model, formulated as a large-scale mathematical program with equilibrium constraints, to assess the impact of (i) different national grid cost allocation regimes and (ii) different cross-border feed-in premium implementations. Our results indicate that EU-wide auctions for renewable electricity should (i) not be based on sliding feed-in premiums and should (ii) ideally be discriminatory if national regulatory conditions differ across Member States. We also consider country-level distributional effects and confirm that Member States can lose when engaging in renewable cooperation.