Explore the vast range of titles available.

\"It helps to derive new and innovative conclusions based on problems. It helps to make the system robust and efficient. It helps to deal with linear and non-linear applications. It gives new insight into the area of research\"-- Provided by publisher.

Two ways of implementing unilateral holonomic constraints with piecewise smooth boundaries are considered. Examples are given that testify both in favor of the proposed methods and against them. The sensitivity of the equilibria of a system subjected to holonomic constraints with piecewise smooth boundaries to the way these constraints are implemented is also discussed using examples. Two problems from the mechanics of systems constrained by a pair of inextensible weightless tethers are considered. In one of these problems, which is most likely academic in nature, equilibria are found and small oscillations near these equilibria are studied. Another problem relates to tethered systems deployed near a uniformly rotating celestial body. For it, the relative equilibria of a load suspended on a pair of tethers are found, and sufficient conditions for the stability of these relative equilibria are studied.

This study investigates whether public procurement mitigates or exacerbates innovative enterprises’ financial constraints. We distinguish between general and environmentally beneficial innovative enterprises. Theory suggests that the treatment effects of public procurement, particularly when mediated by the demand-pull effect, may lower a company’s funding constraints for innovation. We test this theory with extended probit models allowing for endogenous treatment and selection. The findings reveal a significantly positive treatment effect of public procurement on the probability of facing financial constraints in both areas: general and environmentally beneficial innovative activities. Thus, the principal implications of this study are (1) that being an innovating SME exacerbates financial constraints and (2) that strengthening SMEs’ participation in European public tenders would not contribute to lowering SMEs’ financial constraints. On the contrary, complementary grants or other financial incentives might be necessary to substantially increase the SMEs’ bidding rates in public tenders.Plain English SummaryPublic procurement incre ases the chance of innovative firms, in particular SMEs, to face financial constraints. This study investigates whether public procurement mitigates or exacerbates financial constraints of enterprises with general or environmentally beneficial innovative activities. The principal implication is that owning a public procurement contract is no instrument to lower innovative firms’, in particular SMEs’, financial constraints. On the contrary, complementary grants or other financial incentives might be necessary to substantially increase the SMEs’ bidding rates in a public tender.

Accurate positioning is essential for train operational efficiency and automation. Although GNSS/INS/Non-Holonomic Constraints (NHC) integration provides continuous navigation, enforcing NHC during train side-slip, vibration, or track irregularities introduces significant positioning errors. To resolve this, we propose an adaptive NHC-assisted GNSS/INS integrated positioning method. First, an EKF tightly couples GNSS and INS measurements. Crucially, we design an NHC validity detector that constructs a test statistic from NHC observation residuals. This statistic is continuously compared against a detection threshold: NHC constraints are selectively activated only when residuals indicate validity; otherwise, they are automatically disabled to prevent error contamination. Field tests on railway lines demonstrate that the adaptive strategy: reduces lateral positioning RMS error by 11.4% compared to forced-NHC approaches.

To address the complex product-integrated scheduling problem, an improved genetic algorithm based on process constraint matrix and family definition is proposed. The algorithm features a coding method that accurately represents the processing sequence constraints in the product process tree and introduces a simplified method for defining families and sub-processes. On this basis, a hierarchical relationship matrix is derived from the constraint matrix. To resolve the issue of infeasible solutions arising from crossover and mutation operations, a family-based single-parent genetic improvement algorithm is designed. Experimental results validate the effectiveness of the proposed algorithm.

Many constraint satisfaction and optimisation problems can be solved effectively by encoding them as instances of the Boolean Satisfiability problem (SAT). However, even the simplest types of constraints have many encodings in the literature with widely varying performance, and the problem of selecting suitable encodings for a given problem instance is not trivial. We explore the problem of selecting encodings for pseudo-Boolean and linear constraints using a supervised machine learning approach. We show that it is possible to select encodings effectively using a standard set of features for constraint problems; however we obtain better performance with a new set of features specifically designed for the pseudo-Boolean and linear constraints. In fact, we achieve good results when selecting encodings for unseen problem classes. Our results compare favourably to AutoFolio when using the same feature set. We discuss the relative importance of instance features to the task of selecting the best encodings, and compare several variations of the machine learning method.

The purpose of this opinion paper is providing a platform for explaining and discussing the relatedness and nestedness of constraints on the basis of four claims: (a) task constraints are distributed between the person and the environment and hence are relational variables, (b) being relational, task constraints are also emergent properties of the organism/environment system, (c) constraints are nested in timescales, and (d) a vast set of constraints are correlated through circular causality. Theoretical implications for improving the understanding of the constraints-led approach and practical applications for enhancing the manipulation of constraints in learning and training settings are proposed.

This article assesses the status of hierarchical leisure constraints theory (Crawford & Godbey, 1987; Crawford, Jackson, & Godbey, 1991) regarding many issues. Such issues include clarification and elaboration of some aspects of the original model, a review of studies which have used or examined the model and the extent to which they are confirmatory, critiques of the original model by various authors, and avenues for further research. Conclusions drawn include that the model is cross culturally relevant, that the model may examine forms of behavior other than leisure, and that, while research to date has been largely confirmatory, there is a high potential for the theory to be expanded in order to advance leisure constraints research to the next level.

The increasing penetration of new energy sources in new power systems has exacerbated the volatility and complexity of power system currents. Grid planning is facing higher challenges. Established grid planning models usually use the upper and lower limits of grid transmission capacity as constraints, but this may lead to long-term heavy load operation of certain lines and increase system risks. Therefore, this paper designs a line-heavy load rate constraint and establishes a single-objective optimization model for grid planning based on this constraint. Example analyses verify the effectiveness of adding line-heavy load rate constraints in planning and the reasonableness of the single-objective optimization model.

This paper examines the prices of basic staples in rural Mexico. We document that nonlinear pricing in the form of quantity discounts is common, that quantity discounts are sizable for basic staples, and that the well-known conditional cash transfer program Progresa has significantly increased quantity discounts, although the program, as documented in previous studies, has not affected unit prices on average. To account for these patterns, we propose a model of price discrimination that nests those of Maskin and Riley (1984) and Jullien (2000), in which consumers differ in their tastes and, because of subsistence constraints, in their ability to pay for a good. We show that under mild conditions, a model in which consumers face heterogeneous subsistence or budget constraints is equivalent to one in which consumers have access to heterogeneous outside options. We rely on known results to characterize the equilibrium price schedule, which is nonlinear in quantity. We analyze the effect of nonlinear pricing on market participation as well as the impact of a market-wide transfer, analogous to the Progresa one, when consumers are differentially constrained. We show that the model is structurally identified from data on prices and quantities from a single market under common assumptions. We estimate the model using data on three commonly consumed commodities from municipalities and localities in Mexico. Interestingly, we find that relative to linear pricing, nonlinear pricing is beneficial to a large number of households, including those consuming small quantities, mostly because of the higher degree of market participation that nonlinear pricing induces. We also show that the Progresa transfer has affected the slopes of the price schedules of the three commodities we study, which have become steeper as consistent with our model, leading to an increase in the intensity of price discrimination. Finally, we find that a reduced form of our model, in which the size of quantity discounts depends on the hazard rate of the distribution of quantities purchased in a village, accounts for the shift in price schedules induced by the program.