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NPV and IRR are essential components of Corporate Finance and are used for evaluating financial viability of investment projects. However, some serious issues have been raised about existence and uniqueness of IRR. While exploring such issues, we work out the necessary and sufficient condition for existence and uniqueness of IRR for any generalized scenario. Moreover, this condition is fulfilled by the projects considered by practicing managers. This explains why IRR delivers and is so popular among practicing managers. Further, certain applications of the Descartes Rule of Signs to estimate the number of IRRs are found to be erroneous. The correct approach in this regard is outlined, and it gives results consistent with our findings. Our analysis about the ranking of mutually exclusive projects reveals that, as a technique, IRR may claim a preference in this regard. [ABSTRACT FROM AUTHOR]

Copyright of Health Policy & Planning is the property of Oxford University Press / USA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper is concerned with a mean-field type optimal control problem, whose new features are that the state xtv is partially observed by a noisy process y(t), and the control problem is time inconsistent in the sense that Bellman optimality principle does not work. A necessary condition for optimality is derived by convex variation, dual technique and backward stochastic differential equations (BSDEs). A linear-quadratic (LQ) optimal control example is studied, and the optimal solution is obtained by the optimal filtering for BSDEs and the necessary condition. [ABSTRACT FROM AUTHOR]

In this study, finite‐time synchronisation between two chaotic systems with discrete and distributed delays is investigated by using periodically intermittent memory feedback control. Based on finite‐time stability theory, some novel and effective synchronisation criteria of intermittent control are derived by means of linear matrix inequalities and differential inequality techniques. Furthermore, a necessary condition of finite‐time synchronisation of intermittent control is given for neural networks with discrete and distributed delays. A numerical example on two chaotic neural networks shows the effectiveness and correctness of the derived theoretical results. In addition, a secure communication synchronisation problem is presented to demonstrate practical effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The Hamilton cycle problem is closely related to a series of famous problems and puzzles (traveling salesman problem, Icosian game) and, due to the fact that it is NP-complete, it was extensively studied with different algorithms to solve it. The most efficient algorithm is not known. In this paper, a necessary condition for an arbitrary un-directed graph to have Hamilton cycle is proposed. Based on this condition, a mathematical solution for this problem is developed and several proofs and an algorithmic approach are introduced. The algorithm is successfully implemented on many Hamiltonian and non-Hamiltonian graphs. This provides a new effective approach to solve a problem that is fundamental in graph theory and can influence the manner in which the existing applications are used and improved. [ABSTRACT FROM AUTHOR]

The paper deals with the problem of distinction between knowledge and true belief in Plato's dialogue Theaetetus. It is focused on the part Theaet. 201a-c, where according to some commentators, Plato specified the necessary and sufficient conditions for achieving knowledge. The aim of the paper is to find out, whether talking about necessary or sufficient conditions is relevant in the wider context of the other dialogues and also in Theaetetus itself. [ABSTRACT FROM AUTHOR]

We study a linear delay differential equation with a single positive and a single negative term. We find a necessary condition for the oscillation of all solutions. We also find sufficient conditions for oscillation, which improve the known conditions.

In this article the standard philosophical method involving intuition-driven conceptual analysis is challenged in a new way. This orthodox approach to philosophy takes analysanda to be the specifications of the content of concepts in the form of sets of necessary and sufficient conditions. Here it is argued that there is no adequate account of what necessary and sufficient conditions are. So, the targets of applications of the standard philosophical method so understood are not sufficiently well understood for this method to be dependable. [ABSTRACT FROM AUTHOR]

This article discusses the control system of fractional endpoint variable variational problems. For this problem, we prove the Euler-Lagrange type necessary conditions which must be satisfied for the given functional to be extremum. Finally, one example is provided to show the application of our results. [ABSTRACT FROM AUTHOR]

In this article, we present a necessary condition and a necessary and sufficient condition for a class of functions to be completely monotonic. [ABSTRACT FROM AUTHOR]

This paper revisits the stochastic near-optimal control problem considered in Zhou (1998), where the stochastic system is given by a controlled stochastic differential equation with the control variable taking values in a general control space and entering both the drift and diffusion coefficients. A necessary condition of near-optimality is derived using Ekeland’s variational principle, spike variation techniques, and some delicate estimates for the state and the adjoint processes. We improve the error bound of order from “almost” ε 1 3 in Zhou (1998) to “exactly” ε 1 3 . [ABSTRACT FROM AUTHOR]

Both power flow states and sensitivities between variables are important information in power system analysis and should be kept consistent before and after equivalence. The general sufficient and necessary condition for sensitivity consistency in equivalent methods is derived. Based on the proposed general condition, it is further derived that Thevenin equivalent method can keep sensitivity consistent before and after equivalence, whereas the specific preconditions for sensitivity consistency are required for the traditional Ward equivalent method and extended Ward equivalent method. These two Ward equivalent methods cannot meet the preconditions in general cases and may lead to significant errors. This conclusion is confirmed by simulation results of the IEEE 39‐bus system and an actual power system with 661 buses. [ABSTRACT FROM AUTHOR]

This article studies a synchronised output regulation (SOR) problem exchanging information at sampled time. Each node has a continuous‐time internal model controller and a local exosystem providing a reference output signal. At sampled time, each node sends the exosystem state to its neighbouring nodes, as well as updates the exosystem dynamics by the received sampled data. A necessary and sufficient condition that the sampled period should satisfy for SOR with fixed digraph and time delay is presented. A numerical simulation shows an efficacy of analytic results. [ABSTRACT FROM AUTHOR]

In this paper, we explore the impact of wireless channel capacity on asymptotic detection performance for distributed detection in wireless sensor networks (WSNs). As a key performance metric for large-scale WSNs, the asymptotic detection performance is characterized by the error exponents of detection error probabilities. In particular, we consider error exponents under dependent observations and nonideal channels. We derive a sufficient condition under which the detection system will result in zero error exponents under both orthogonal channels and multiple-access channels. We show that if the channel capacity is zero, the corresponding error exponents become zero as well. In addition, a special case of dependent observations where sensor measurements are independently identically distributed given a hidden variable or vector is studied. Under this model, we further derive the necessary and sufficient condition for having zero error exponents. Numerical examples are also presented to validate the results and demonstrate the relationship among the asymptotic detection performance and system parameters. [ABSTRACT FROM PUBLISHER]

This study investigates the cooperative linear output regulation problem of heterogeneous multi‐agent systems with periodic switching topologies. A novel distributed adaptive control law is presented based on dynamic state feedback with the feedback gain independent of the Laplacian matrix of the underlying system communication topology. It is shown that the cooperative output regulation problem can be solved under a necessary and sufficient condition. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed control law. [ABSTRACT FROM AUTHOR]

The optimal pixel expansion is an important parameter of deterministic visual cryptography scheme (DVCS). There are many researches have been done under different access structures and stacking operations. However, any necessary or sufficient condition has not been found about the optimal pixel expansion. In this paper, we give a necessary condition of the optimal pixel expansion of DVCS for the first time, which is suitable for any access structure and any stacking operation. Furthermore, a pixel expansion optimization algorithm has been designed to improve the existing schemes. It is found that the pixel expansion can be reduced for most DVCS based on XOR operation. Finally, we give some experimental results and comparisons to show the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

Human being assistant transportation systems have received much attention in recent years. This study proposes a wheeled human transportation vehicle (WHTV). Two‐wheeled vehicles have been known as powerful transporters for urban areas. Based on a low‐level microprocessor, a WHTV is designed and implemented in this study. Moreover, a Mamdani‐like output recurrent fuzzy controller (MLORFC) is used to control the WHTV in this study. As the MLORFC obtains system dynamics, it is better than the traditional Mamdani‐type fuzzy controllers in terms of dynamic response. A necessary condition based on the Lyapunov stability analysis is established to guarantee the system stability. The recurrent weights are tuned on‐line using the dynamic gradient descent method. The learning rates of the recurrent weights are automatically settled based on a Lyapunov analytical method to achieve the system error convergence. The experiment results in Section 4 show that the conveyance platform can stably move under the proposed control strategy. [ABSTRACT FROM AUTHOR]

This study is concerned with the infinite horizon H2 /H∞ control of time‐varying stochastic discrete‐time systems with state and disturbance dependent noise. The notion of uniform detectability for time‐varying stochastic discrete‐time systems is introduced, and some good properties are derived. Under uniform detectability, a necessary and sufficient condition for the existence of time‐varying stochastic H2 /H∞ control is presented, which transforms the design of H2 /H∞ control into the solvability of coupled time‐varying matrix‐valued equations. Finally, an iterative algorithm is proposed to solve the coupled time‐varying matrix‐valued equations, and a numerical example is provided to show the effectiveness of the obtained results. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to consider the necessary and sufficient conditions of wave packet systems to be frames in higher dimensions. We establish the necessary and sufficient conditions for all kinds of wave packet frames of the different operator order in L²(Rn) with an arbitrary expanding matrix dilations, which include the corresponding results of wavelet analysis and Gabor theory as the special cases. Our way combines with some techniques in wavelet analysis and time-frequency analysis. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to consider the necessary and sufficient conditions of wave packet systems to be frames in higher dimensions. We establish the necessary and sufficient conditions for all kinds of wave packet frames of the different operator order in L²(Rn) with an arbitrary expanding matrix dilations, which include the corresponding results of wavelet analysis and Gabor theory as the special cases. Our way combines with some techniques in wavelet analysis and time-frequency analysis. [ABSTRACT FROM AUTHOR]

In our preceding paper [Sun B, Wu MX. Appl. Anal. 2013;92:901–921], we investigated an optimal control problem of age-structured population dynamics for spread of universally fatal diseases and derived the necessary optimality condition for the problem in fixed final horizon case. As a follow-up, in this paper, under weaker additional conditions, we address ourselves to the investigation of the foregoing system in free final horizon case and present further new results of current interests. [ABSTRACT FROM PUBLISHER]

To explore the crucial driving forces and dynamics of the Chinese apparel industry cluster, the authors analysed current situations, characteristics and the dilemma in the Chinese apparel industry based on surveys conducted in the Yangtze River Delta. This study classified the factors impacting apparel industry cluster development into necessary conditions and evolutionary factors according to logistic differential equation, and proposed a dynamics model framework of apparel industry cluster with positive and negative feedback mechanism. The authors believe that the Chinese apparel industry cluster is an ecology system involving outsourcing, specialisation agglomerating, competition, resource complementary, etc. and has a quick response ability of adapting to environment. [ABSTRACT FROM AUTHOR]

A rigorous definition of semi-Markov dependent risk model is given. This model is a generalization of the Markov dependent risk model. A criterion and necessary conditions of semi-Markov dependent risk model are obtained. The results clarify relations between elements among semi-Markov dependent risk model more clear and are applicable for Markov dependent risk model. [ABSTRACT FROM AUTHOR]

In this paper, we consider two-components nonlinear Schrödinger equations in the super critical case. We establish a necessary condition and a sufficient condition of global existence of the solution for two-components nonlinear Schrödinger equations. These conditions are charge criterion of global existence in the super critical case, thereby extending the results in the critical case. Furthermore, we improve a blow-up condition. [ABSTRACT FROM AUTHOR]

In this paper, we deal with the adiabatic approximation of general Hamiltonians by splitting it into two parts, with one part a Hamiltonian that has at least one time-independent eigenstate up to a phase factor. We first develop the method of finding this kind of Hamiltonians. Then the relationship between adiabatic approximation and these Hamiltonians is discussed. Applying this to a general case, we give both a necessary condition and a sufficient condition for adiabatic approximation, followed by a spin-half example to illustrate. [ABSTRACT FROM AUTHOR]

We improve and extend sufficient conditions for an optimal solution to happen at a fixed point in a single facility minisum location model with mixed transportation modes recently proposed and studied by Brimberg, Love and Mladenović. In particular, conditions are derived that are valid for general mixed metrics, while for mixed ℓ-norms, possibly with rotated axes, much stronger conditions are obtained. An example demonstrates the superiority of the new conditions. [ABSTRACT FROM AUTHOR]

In organizational research the object of study is often a process, that is, a complex of events and activities that unfolds over time. In this chapter we focus on temporally ordered configurations, which can be defined as those configurations in which conditions occur in a specific temporal order. We illustrate the aims, characteristics, and limitations of several approaches that have been proposed as tools for the analysis of temporal order. Our illustration involves an analysis of the "gestation activities" of nascent entrepreneurs, that is, persons involved in the creation of a new firm. We aim to identify temporal sequences of gestation activities that generate or allow a successful outcome of the gestation process, while an occurrence of the same activities in another temporal order will not generate or allow that outcome. First we discuss Event Structure Analysis and Optimal Matching and conclude that these approaches cannot provide the kind of analysis that we are aiming at in this chapter. Then we discuss Temporal Qualitative Comparative Analysis, for which our analysis points to technical limitations that constrain its application. We then present and discuss an alternative approach, Temporal Necessary Condition Analysis. [ABSTRACT FROM AUTHOR]

Copyright of Revista Chilena de Derecho is the property of Revista Chilena de Derecho and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article is concerned with the optimal control problem of age-structured population dynamics for the spread of universally fatal diseases. The existence and uniqueness of solution of the system, which consists of a group of partial differential equations with nonlocal boundary conditions, is proved. The Dubovitskii and Milyutin functional analytical approach is adopted in the investigation of the Pontryagin maximum principle of the system. The necessary condition is presented for the optimal control problem in fixed final horizon case. Finally, a remark on how to utilize the obtained results is also made. [ABSTRACT FROM PUBLISHER]

Abstract: Random context grammars belong to the class of context-free grammars with regulated rewriting. Their productions depend on context that may be randomly distributed in a sentential form. Context is classified as either permitting or forbidding, where permitting context enables the application of a production and forbidding context inhibits it. We have proven a pumping lemma for random permitting context languages and a shrinking lemma for random forbidding context languages. We now present new necessary conditions for both these classes of languages and illustrate them with examples. We also present and illustrate a new necessary condition for context-free languages. [Copyright &y& Elsevier]

In this paper, we study two subclasses V(α,λ,g) and W(α,λ,g) of holomorphicfunctions f(z) in the open unit disk U associated with some holomorphic function g(z). The object of the present paper is to drive some interesting conditions and necessary conditions for f(z) belonging to the classes V(α,λ,g) and W(α,λ,g) and some results of Jack's Lemma [3]. [ABSTRACT FROM AUTHOR]

This paper is concerned with optimal control problem whose state equation is an uncertain differential equation. A necessary condition of optimality for uncertain optimal control problem is presented by using classical variational method. Meanwhile, an existence theorem of solution to backward uncertain differential equation is proved. [ABSTRACT FROM AUTHOR]

Abstract: Non-unique solutions of inverse problems arise from a lack of information that satisfies necessary conditions for the problem to be well defined. This paper investigates these conditions for inverse modeling of water flow through multi-dimensional variably saturated porous media. It shows that in order to obtain a unique estimate of hydraulic parameters, along each streamline of the flow field (1) spatial and temporal head observations must be given; (2) the number of spatial and temporal head observations required should be greater or equal to the number of unknown parameters; (3) the flux boundary condition or the pumping rate of a well must be specified for the homogeneous case and both boundary flux and pumping rate are a must for the heterogeneous case; (4) head observations must encompass both saturated and unsaturated conditions, and the functional relationships for unsaturated hydraulic conductivity/pressure head and for the moisture retention should be given, and (5) the residual water content value also need to be specified a priori or water content measurements are needed for the estimation of the saturated water content. For field problems, these necessary conditions can be collected or estimated but likely involve uncertainty. While the problems become well defined and have unique solutions, the solutions likely will be uncertain. Because of this uncertainty, stochastic approaches are deemed to be appropriate for inverse problems as they are for forward problems to address uncertainty. Nevertheless, knowledge of these necessary conditions is critical to reduce uncertainty in both characterization of the vadose zone and the aquifer, and prediction of water flow and solute migration in the subsurface. [Copyright &y& Elsevier]