Constant Cost Research Articles

Verifiable data streaming with efficient update for intelligent automation systems

The wide deployment of Internet of Things (IoT) devices enables the controller to continuously collect massive volume data in automation systems, and makes it possible to make intelligent decisions based on machine learning techniques. In fact, data-driven intelligent automation systems have been common in the industrial community. Nevertheless, how to effectively store the collected stream data and ensure their integrity is still challenging. To this end, the notion of verifiable data streaming (VDS) protocol, which enables a client to outsource the stream data to an untrusted server in a verifiable manner, was introduced. However, we argue that existing VDS protocols based on the chameleon authentication tree (CAT) are inefficient in the data update, since the whole CAT must be updated accordingly to avoid acute exposure of chameleon hashing. Thus, they are infeasible for intelligent automation systems that need to frequently update data. In this article, we first introduce a new primitive called double-trapdoor chameleon hash tree (DCHT) based on the double-trapdoor chameleon hash families, where each leaf of DCHT is calculated and fixed by using a double-trapdoor chameleon hash family, making the entire DCHT always unchanged. Furthermore, we propose a novel VDS protocol based on the DCHT. Due to the distinctive properties of the underlying DCHT, the proposed VDS protocol has a constant update cost and more efficient than previous VDS protocols based on CAT. Besides, we prove that the proposed VDS protocol is secure in the standard model.

Disability and workers' compensation trends for employees with mental disorders and SUDs in the United States.

IntroductionUS employee absence benefits may include workers' compensation (WC) for work-related injuries/illnesses, short- and long-term disability (STD and LTD, respectively) for non–work-related injuries/illnesses, and discretionary sick leave (SL). Absences can significantly impact business performance, and employers are intensifying efforts to manage benefits and connections with employee health. This research compares all-cause STD/LTD/WC/SL use and variation from baseline (2002) for eligible employees (EMPs) with mental disorders (MDs) and SUDs to determine if use/payments varied over time.MethodsEmployees incurring medical claims with Agency for Healthcare Research and Quality MD and SUD ICD-9/10 codes were identified in the WorkPartners database (January 1, 2002 to December 31, 2019). Retrospective analysis was performed on annual prevalence, benefit use, mean days of leave, and median payments as a percent of salary (including lump-sum distributions and potentially extending beyond initiation year). WC claims without work absences were excluded. For each benefit, annual outcomes were calculated as a percent of baseline to show variability.ResultsUse was 48.1% to 202.2% (median, 102.8%) of baseline rates for SL (SUD-EMPs), and 87.3% to 108.4% (median, 97.3%) for STD (MD-EMPs). Days of LTD leaves were 21.5% to 657.8% (median, 359.2%) of baseline days (MD-EMPs), and 122.7% to 1042.2% (median, 460.0%) of baseline days for (SUD-EMPs). Median payments for WC were 78.6% to 253.6% (median, 114.6%) of baseline (MD-EMPs) and 97.9% to 481.6% (median, 104.0%) for SUD-EMPs.DiscussionEmployees with MD/SUD used absence benefits at differing rates over time with varying days of leave and payments as a percent of salary. Using a constant cost or salary replacement factor over time for all benefits is not accurate or appropriate.

Status, trend, economic and environmental impacts of household solar photovoltaic development in China: Modelling from subnational perspective

Distributed solar PV contributes one third to total solar power generation in China, but household solar PV (HSPV) currently accounts for only 22% in the distributed solar market. Although researchers have investigated the huge power generation potential of the rooftop system by various estimation techniques and case studies, few has looked deeper into the barriers and pathways to realize that potential. This study builds an analytical framework for HSPV development, which includes a trend analysis module based on the downscaling platform and an impact simulation module based on techno-economic evaluation. Results show that the top four provinces contribute 74% to current installed capacity of HSPV, which represents only 2% of the technical potential. However, with the rapid cost reduction and market expansion, regional development of HSPV would become more balanced. Besides, although HSPV project is economically feasible for 86% of the prefectural cities, the profitability remains to be further enhanced given its current low adoption rate. When environmental and health gains from reduced exposure to air pollution are considered, net benefit is equivalent to 62.8% of the initial investment, and larger net benefit is expected for households from cities in the southern and eastern coastal regions. Finally, it is concluded that constant cost decline brought by technology innovation is still the main driver for the majority of less developed cities in the middle and northern part of China, and more efforts should be devoted to business mode innovation to motivate HSPV investment in more developed cities in the east.

Pricing in make-to-order firms with a lead time-dependent cost

Abstract The existing literature on make-to-order firms typically supposes that the unit production cost is a constant. In contrast, in this study, this cost is a variable that depends on the lead time. Under this assumption, we investigate the pricing problem for both a monopoly firm and two competing firms. Specifically, we develop a queueing-game-theoretic model to capture the interaction between customers and the firm’s manager and further solve the pricing problem. The results illustrate that, for a monopoly firm, there exists a service rate threshold, and for two homogeneous firms, there is a unique symmetric equilibrium. However, for two heterogeneous firms, the equilibrium may not exist, and if it does, it may not be unique. In this case, the equilibrium is characterized analytically if it is unique and explored numerically if not. Finally, a specific cost function is adopted to analyse the sensitivity of the optimal decisions. When the firms have this variable cost, compared with those with constant unit production cost, customers’ waiting time might be shorter, and the competition between firms might be fiercer. Also, for these firms, increasing the service rate or decreasing the cost parameter does not always help to increase their market share or profit.

A Simulation-based Optimization Approach to Logistic and Supply Chain Network Design

The Department of Defense (DoD) operates a world-wide supply chain, which in 2017 contained nearly 5 million items collectively valued at over $90 billion. Since at least 1990, designing and operating this supply chain, and adapting it to ever-changing military requirements, are highly complex and tightly coupled problems, which the highest levels of DoD recognize as weaknesses. Military supply chains face a wide range of challenges. Decisions made at the operational and tactical levels of logistics can alter the effectiveness of decisions made at the strategic level. Decisions must be made with incomplete information. As a result, practical solutions must simultaneously incorporate decisions made at all levels as well as take into account the uncertainty faced by the logistician. The design of modern military supply chains, particularly for large networks where many values are not known precisely, is recognized as too complex for many techniques found in the academic literature. Much of the literature in supply chain network design makes simplifying assumptions, such as constant per-unit transportation costs regardless of the size of the shipment, the shipping mode selected, the time available for the delivery, or the route taken. This article avoids these assumptions to provide an approach the practitioner can use when designing and adapting supply chain networks. This research proposes a simulation-based optimization approach to find a near-optimal solution to a large supply chain network design problem of the scale faced by a theater commander, while recognizing the complexity and uncertainty that the practicing military logistician must deal with.

Optimal scheduling of the next preventive maintenance activity for a wind farm

Abstract. A large part of the operational cost for a wind farm is due to the cost of equipment maintenance, especially for offshore wind farms. How to reduce the maintenance cost, and hence increase profitability, is this article's focus. It presents a binary linear optimization model whose solution may inform the wind turbine owners about which components, and when, should undergo the next preventive maintenance (PM) replacements. The suggested short-term scheduling strategy takes into account eventual failure events of the multi-component system – in that after the failed system is repaired, the previously scheduled PM plan should be updated, assuming that the restored components are as good as new. The optimization algorithm of this paper, NextPM, is tested through numerical case studies applied to a four-component model of a wind turbine. The first study addresses the important case of a single component system, used for parameter calibration purposes. The second study analyses the case of seasonal variations of mobilization costs, as compared to the constant mobilization cost setting. Among other things, this analysis reveals a 35 % cost reduction achieved by the NextPM model, as compared to the pure corrective maintenance (CM) strategy. The third case study compares the NextPM model with another optimization model – the preventive maintenance scheduling problem with interval costs (PMSPIC), which was the major source of inspiration for this article. This comparison demonstrates that the NextPM model is accurate and much faster in terms of computational time.

Efficient performance by companies with mixed ownership: Privatization and divestiture of a vertically integrated public monopoly

AbstractThis paper examines a model of privatization and divestiture of a vertically integrated public monopoly. The framework is used to derive general conditions of how mixed companies might be used to promote efficient outcomes without assuming either an ideal social planner or superior cost performance of private enterprise. The conditions suggest that efficient public policy towards mixed (public‐private partnership) companies depends on basic cost and demand conditions. The results indicate that: (1) a vertically integrated private monopoly can be more efficient than any combination of mixed companies when there is a sufficiently flat linear (elastic) demand curve and relatively greater (upward sloping) marginal cost for the downstream sector; (2) an upstream public and downstream public firm can achieve the first best outcome when the downstream firm has constant marginal costs; and (3) a partial privatization of the upstream firm achieves higher welfare than taking that action for the downstream firm. The intuition behind the propositions is provided using standard features of cost and demand. While the implications for public policy regarding privatization and divestiture in infrastructure sectors are not definitive, the results underscore the importance of understanding cost and demand conditions when developing and implementing public policies.

PGI25 Long- and Short-Term Disability and Workers' Compensation Trends for Employees with Digestive System (Gastrointestinal) Conditions in the United States

Use objective data to compare patients’ all-cause short-term disability (STD), long-term disability (LTD) and workers' compensation (WC) utilization and explore changes from baseline for employees with gastrointestinal (digestive system) conditions. Employees with gastrointestinal medical-claims in the US Agency for Healthcare Research and Quality digestive system category were retrospectively identified in WorkPartners Research Reference Database(RRDb) from 2001—2019. Each year the analysis focused on the percent of patients with gastrointestinal-conditions, and by absence benefit, the percent of eligible employees utilizing the benefit, mean leave-length (days) and median payments as percent of salary (MedianPay). Disability+WC payments included lump-sum distributions and potentially extended beyond the year initially incurred. Workplace accidents were paid under the WC benefit. WC claims without absence from work (medical-only) were excluded. Sick leave claims may be taken for any reason and were excluded. All employees’ absences were aggregated based on the initiation-year. For each benefit, average leave-length and MedianPay were calculated and compared with baseline(2001). At baseline (2001), 8.4% of employees had gastrointestinal conditions; of these, 12.4% filed STD-claims lasting 37.53 mean-days at 70.5% MedianPay, 0.5% filed LTD-claims lasting 194.27 mean-days at 19.6% MedianPay, and 1.5% filed WC-claims lasting 53.99 mean-days at 67.2% MedianPay. From 2002—2019, 7.1%—10.2% of employees had gastrointestinal conditions. Of these, 10.4%—16.5% of eligible employees filed STD claims lasting 80.8%—119.8% of baseline-days (BDs) and paying 68.6%—127.7% MedianPay; 0.6%—1.4% of eligible employees filed LTD claims lasting 61.2%—368.0% of BDs at 115.1%—305.7% MedianPay; 0.5%—1.5% of eligible employees filed WC claims lasting 128.1%—327.6% of BDs at 78.3%—175.6% MedianPay. MedianPay was highest in 2013(STD), 2002(LTD), and 2003(WC). Claims-lengths were longest in 2019(STD), and 2006(LTD) and 2010(WC). Employees with gastrointestinal diseases used different absence benefits over time with varying leave lengths and payments as a percent of salary. Using a constant cost over time for all benefits is not accurate or appropriate.

PMS33 Long- and Short-Term Disability and Workers' Compensation Trends for Employees with Systemic Lupus Erythematosus or Connective Tissue Disorders in the United States

Use objective data to compare employees’ all-cause short-/long-term disability (STD and LTD, respectively) and workers' compensation (WC) utilization, and explore changes from baseline for employees with Systemic Lupus Erythematosus and Connective Tissue Disorders (Lupus/CTD). Employees with medical-claims for the US Agency for Healthcare Research and Quality Lupus/CTD category were retrospectively identified each year in WorkPartners Research Reference Database from 2001—2019. Each year the analysis focused on the %-of-employees with medical-claims, average Charlson-Comorbidity-Index-Score (CCI), and by benefit, the %-of-eligible employees utilizing the benefit, mean leave-length(in-days) and median payments as a %-of-salary (MedianPay). Disability/WC-payments included lump-sum-distributions and potentially extended beyond the year initiated. Workplace-accidents were paid under the WC-benefit. WC-claims without absence from work(medical-only) were excluded. Sick-leave claims may be taken for any reason and were excluded. All employees’ claims were included based on the initiation-year. For each benefit, average leave-length and MedianPay were calculated and compared with baseline (2001). At baseline(2001), 0.3% of employees had Lupus/CTD medical-claims (CCI=1.28); 18.2% filed STD-claims lasting 47.04 mean-days at 62% of MedianPay, 1.0% filed LTD-claims lasting 198.2 mean-days at 59.4% of MedianPay, and 1.2% filed WC-claims lasting 95.86 mean-days at 121.2% of MedianPay. From 2002—2019: 0.19%-0.33% of employees had Lupus/CTD with CCIs from 1.29—1.70, 10.7%—22.6% of eligible-employees filed STD-claims lasting 70.4%—125.0% of baseline-days(BDs) at 37.3%—95.3% of baseline-MedianPay; 0.5%—3.1% of eligible-employees filed LTD-claims lasting 22.3%—1094.2% of BDs at 9.6%—191.4% of baseline-MedianPay; 0%—1.3% of eligible-employees filed WC-claims lasting 16%—271.2% of BDs at 47.1%—879.4% of baseline-MedianPay. MedianPay was highest in 2004(STD), 2012(LTD), and 2008(WC). Claims-lengths were longest in 2017(STD), 2004(LTD), and 2007(WC). Systemic Lupus Erythematosus and Connective Tissue Disorders are rare disorders. Employees with Lupus/CTD used different absence benefits over time with varying leave-lengths and median-payments as a %-of-salary. Using a constant cost or salary-replacement factor over time for all benefits is not accurate or appropriate.

Granular Data Access Control with a Patient-Centric Policy Update for Healthcare.

Healthcare is a multi-actor environment that requires independent actors to have a different view of the same data, hence leading to different access rights. Ciphertext Policy-Attribute-based Encryption (CP-ABE) provides a one-to-many access control mechanism by defining an attribute’s policy over ciphertext. Although, all users satisfying the policy are given access to the same data, this limits its usage in the provision of hierarchical access control and in situations where different users/actors need to have granular access of the data. Moreover, most of the existing CP-ABE schemes either provide static access control or in certain cases the policy update is computationally intensive involving all non-revoked users to actively participate. Aiming to tackle both the challenges, this paper proposes a patient-centric multi message CP-ABE scheme with efficient policy update. Firstly, a general overview of the system architecture implementing the proposed access control mechanism is presented. Thereafter, for enforcing access control a concrete cryptographic construction is proposed and implemented/tested over the physiological data gathered from a healthcare sensor: shimmer sensor. The experiment results reveal that the proposed construction has constant computational cost in both encryption and decryption operations and generates constant size ciphertext for both the original policy and its update parameters. Moreover, the scheme is proven to be selectively secure in the random oracle model under the q-Bilinear Diffie Hellman Exponent (q-BDHE) assumption. Performance analysis of the scheme depicts promising results for practical real-world healthcare applications.

An evolutionary game theoretic model of whistleblowing behaviour in organizations

Abstract We present a theoretical model of corruption in organizations. Our specific focus is the role of incentives that aim to encourage whistleblowing behaviour. Corruption is modelled as a social norm of behaviour using evolutionary game theory. In particular, the dynamics of whistleblowing behaviour is captured using the replicator dynamics equation with constant and quadratic monitoring costs. We formally explore the local asymptotic stability of the equilibria. Our findings indicate that the traditional recommendations of the Beckerian approach are usually too expensive and/or unstable. We argue that an efficient mechanism for controlling corruption can be achieved by maintaining efficient salaries and imposing high rewards for whistleblowers when they detect wrongdoing. In the long term, employees can only be honest, or corrupt, or corrupt and whistleblowers; honest and whistleblowing behaviour will not coexist in the long run, since one of these two strategies is always dominated by the other.

Local Stability of Cournot Equilibrium as the Number of Firms Increases

In this paper, a Cournot oligopoly with isoelastic demand function and constant marginal cost is considered. The local stability conditions of the Cournot equilibrium are determined for four models with different decision mechanisms. In the first model, firms adjust their outputs using the best reply response with naive expectations. The second model is a generalization of the first one, where firms have adaptive expectations. Meanwhile, the third and fourth models adopt the bounded rationality and local monopolistic approximation, respectively. The results show that, in the case of identical firms, the Cournot equilibrium is always stable when the firms adopt the local monopolistic approximation mechanism.

Computation and communication efficient secure group key exchange protocol for low configuration system

The group key exchange protocol is a cryptographic mechanism is designed to provide a common session key for a group, there are some common challenges to this type of algorithm as computation and communication cost. Whenever the involvement of high computation and communication operations to the algorithms encounter, then the system with low configuration always faces problem in major time delay. The proposed approach is designed specifically to provide computation and communication efficient algorithms for low configuration systems without violating the security. For making our approach computationally efficient, we replaced modular exponential operation by modular multiplication operation, helpful for low configuration system making task early. For making our approach communication efficient, we used the divide and conquer mechanism to reduced the message transmission cost. The major task is to generate a common session key for the group in less computation time for a low configuration system without violating the security. The RSA algorithm assuring security with constant computation cost while the modular multiplication operation, assuring the less computation cost for low configuration system. The major limitation of the study as the approach is more efficient and applicable for low configuration system only, if comparing the existing approaches with the low configuration system.

Bayesian force fields from active learning for simulation of inter-dimensional transformation of stanene

We present a way to dramatically accelerate Gaussian process models for interatomic force fields based on many-body kernels by mapping both forces and uncertainties onto functions of low-dimensional features. This allows for automated active learning of models combining near-quantum accuracy, built-in uncertainty, and constant cost of evaluation that is comparable to classical analytical models, capable of simulating millions of atoms. Using this approach, we perform large-scale molecular dynamics simulations of the stability of the stanene monolayer. We discover an unusual phase transformation mechanism of 2D stanene, where ripples lead to nucleation of bilayer defects, densification into a disordered multilayer structure, followed by formation of bulk liquid at high temperature or nucleation and growth of the 3D bcc crystal at low temperature. The presented method opens possibilities for rapid development of fast accurate uncertainty-aware models for simulating long-time large-scale dynamics of complex materials.

ANALYSIS OF THE MANAGEMENT OF MATERIAL AND TECHNICAL ASSETS OF ENTERPRISES

Variability of demand for goods, depending on their availability and cost is a frequently observed phenomenon in the sphere of production and consumption. This paper discusses the possibility of using the ABC analysis for the inventory management system. This type of analysis makes it possible to apply various methods of inventory management for increasing the income and reducing the costs of particular products for manufacturers.
 As is known, the management process approach emphasizes the systematic study of management by defining management functions in an organization and then examining each in detail. There is a general agreement on the planning, organizing, and controlling functions.
 Traditional inventory management systems, such as the Lean Order Quantity (EOQ) model, are based on the assumptions of constant demand rate, constant inventory cost, and instant order. The EOQ assumption of instant order receipt means that the entire order quantity, that is, all units of the purchased lot is immediately received from the supplier. The Economic Production Quantity (EPQ) model weakens this assumption by including incremental order receipt, i.e. debit.
 In recent years, major advances in the sphere of management include the following elements:
 process approach
 management science
 decision support approach,
 scientific approach to human resources development, and sustainable competitive advantage.
 These four approaches complement one another in current practice and provide a useful framework for project management.
 This paper presents a realistic model of the goods production and their inventory, since ABC analysis or ABC classification is an integral part of materials management. According to this approach, the inventory is divided into three categories depending on income generation. The ABC analysis helps entrepreneurs identify the main types of products in the warehouse, prioritize the goods management based on their cost, and analyze customer demand for a specific product.

Technology basis of digital business-model with land assessment function

The chief purpose of the investigation was the creation and theoretical foundation of the main features of the technology basis of digital agrarian business-model, which allows to estimate the value of the useable land. Methodological information was theories of constant accounting, technological theories of scientific revolutions, and theories of stages of economic growth. We applied abstract-logical technique of research, modeling methods, formalization procedure and another approaches. The database included tables of annual accounting reports of agricultural organizations and technological maps of crop cultivation. We suggest the term "Technology basis of the digital agrarian business-model," which constitute a combination of three factors of agricultural production, which are closely related. These factors are soil fertility and technological attributes of lands; climate indicators; innovative technologies which use geographic information systems. The most important part of the technology basis of the agrarian business-model is the process maps of crop cultivation, which used as digital twins of real production processes. However, the basis also includes the annual accounting report of agricultural organizations using the software products of the 1C platform after their adaptation. Adaptation of 1C-accounting platform applications means the separation agricultural procedures and production costs between their variable and constant costs (this step is necessary to calculate the efficiency of applied technologies and economic assessment of used land), the creation of a cluster for technological monitoring and forecast of crop yield, as well as the introduction of a managing cluster in application. This last one is capable of evaluating the effectiveness of various innovative products, optimizing the use of available resources, combining the technological module with the geographic information environment. The main function of technology basis is to estimate the value of the used land based on balance between the correlation of natural to artificial fertility of soils and the correlation of constant to variable costs.

Design, analysis and performance evaluation of parallel algorithms for solving triangular linear systems on multicore platforms

In this paper, we focus on the schedulings of 2-steps graph with constant task cost obtained when parallelizing algorithm solving a triangular linear system. We present three scheduling approaches having the same least theoretical execution time. The first is designed through solving a 0-1 integer problem by Mixed Integer Programming (MIP), the second is based on the Critical Path Algorithm (CPA) and the third is a particular Column-Oriented Scheduling (COS). The MIP approach experiments were carried out and confirmed that the makespan values of the MIP scheduling coincide with those of the corresponding lower bound already reached. Experimental results of the last two approaches detailing both makespans and efficiencies are presented and show that their practical performances differ though they are theoretically identical. We compare also these results to those of the appropriate procedure into so-called PLASMA library (Parallel Linear Algebra for Scalable Multi-core Architectures).

Relative Prices, Comparative Advantage, and Trade Patterns with Three or More Countries and Goods

The present paper shows relative price competition with constant cost production for three or more countries and goods can lead to a wide variety of complex trade patterns. The universal McKenzie-Jones efficiency in the global unit input matrix reduces to relative prices of efficient goods. Specialization requires the unlikely condition of global comparative advantage involving relative prices of all goods. Relative price competition can lead countries to diversify exports, import and export the same good, not trade, and form separate trade groups. The analysis extends restrictions on trade patterns due to inconsistent relative wages.

Discovery, disclosure, and confidence

With the procedural tools of discovery and disclosure available, why would a plaintiff and a defendant fail to both understand the merits of the case and settle it out of court? I analyze a model in which initially the defendant has complete information about the case whereas the plaintiff knows nothing but can learn any fraction of the information, at no cost to himself, through discovery, after which the defendant can disclose any fraction of the remaining information at a constant marginal cost. The plaintiff may underutilize discovery so as to have a chance of privately identifying the defendant's type while still outwardly maintaining his belief that the defendant may have a weak case. For a defendant with a strong case, incomplete discovery can make it excessively costly to signal his strength through a high level of disclosure and excessively risky to signal his strength through a low settlement offer. I show that, in that situation, the availability of discovery actually decreases the probability of settlement.

On the costly voting model: the mean rule

In this paper, we study a model in which a policy is chosen by a group of people through the formation of a committee. Attending the committee is costly, and each person decides whether to take part in it or not. Our work complements Osborne, Rosenthal and Turner (2000) since we allow various types of costs. We work with the mean compromise function, and we do not restrict the distribution of the favourite policy of the group members. Under these assumptions, we establish the existence of pure Nash equilibrium and show that, in comparison to the case of the median compromise function, the outcome of the committee’s work is less random and is not likely to be extreme. In the case of constant costs of participation, we show that when the costs increase, the size of the equilibrium committee decreases and the spread of the outcomes increases.