Switching Policy Research Articles

Fault detection and fault-tolerant control of actuators and sensors in distributed parameter systems

This paper proposes the architecture for fault detection and fault-tolerant control for distributed parameter systems with control actuators and measurement sensors. In the development of this architecture, it is assumed that the system contains multiple actuators and sensors with only one actuator and partial sensors are activated while keeping the remaining actuators and sensors dormant. For the approximate finite-dimensional model, a detection observer with a time-varying threshold is proposed to ensure the actuator faults can be detected. An actuator switching policy is used to arrange switching from faulty actuators to healthy ones based on performance enhancement arguments. To facilitate actuator fault diagnosis, an adaptive observer that accommodates actuator fault is designed. Residuals are defined so as to detect the sensor fault. Then, an integrated fault detection and fault-tolerant control architecture of actuators and sensors is taken into account in the implementation of the infinite-dimensional system on the basis of the singular perturbation formulation. Finally, the proposed theoretical results are verified through an example of chemical reaction.

Secure Communication via a Wireless Energy Harvesting Untrusted Relay

The broadcast nature of the wireless medium allows unintended users to eavesdrop on confidential information transmission. In this regard, we investigate the problem of secure communication between a source and a destination via a wireless energy harvesting untrusted node that acts as a helper to relay the information; however, the source and destination nodes wish to keep the information confidential from the relay node. To realize the positive secrecy rate, we use destination-assisted jamming. Being an energy-starved node, the untrusted relay harvests energy from the received radio-frequency (RF) signals, which include the source's information signal and the destination's jamming signal. Thus, we utilize the jamming signal efficiently by leveraging it as a useful energy source. At the relay, to enable energy harvesting and information processing, we adopt power splitting (PS) and time switching (TS) policies. To evaluate the secrecy performance of this proposed scenario, we derive analytical expressions for two important metrics, viz., the secrecy outage probability and the ergodic secrecy rate. The numerical analysis reveals design insights into the effects of different system parameters such as PS ratio, energy harvesting time, target secrecy rate, transmit signal-to-noise ratio (SNR), relay location, and energy conversion efficiency factor, on secrecy performance. Specifically, the PS policy achieves better optimal secrecy outage probability and optimal ergodic secrecy rate than that of the TS policy at higher target secrecy rate and transmit SNR, respectively.

Abstract 126: The Association Between Medication Aherence and Time in Therapeutic Range (TTR) Among Patients with Atrial Fibrillation Treated With Warfarin: Lessons From the Parkland Health and Hospital System

Background: Therapeutic anticoagulation with Warfarin among patients with atrial fibrillation reduces the risk of stroke. To achieve this risk reduction, it is important that the TTR is > 65%. Novel oral anticoagulants are noninferior or superior to Warfarin in reducing the risk of stroke and do not require maintaining a narrow therapeutic window. The goals of this study were to determine the TTR in a safety-net hospital system as well as predictors of poor TTR. Second, we set out to determine the association between medication nonadherence and TTR. If nonadherence is a significant independent predictor of TTR, this implies that a universal policy of switching to NOACs without considering patient adherence may not improve outcomes. Methods: We queried the Parkland Health and Hospital System electronic medical record for all patients from January 2010 to 2016 with a diagnosis of atrial fibrillation or flutter on EKG who were on warfarin and had INR results available during the study period. TTR was calculated using the Rosendaal method. Patients were grouped into TTR quartiles. Adherence to Warfarin was defined by the proportion of days covered to the medication (0 – 100%). Multivariable linear regression modeling was used to assess the associations between demographic, comorbid conditions, and adherence and TTR. Results: A total of 2,626 patients were included in the analysis. There was significant variability in the TTR with the median TTR of 50% and IQR of 31 - 66. Younger age, black race, alcohol and drug use history, use of antiplatelet medications, and systolic blood pressure >160 was associated with having TTR in the lowest quartile (<31%). Medicare status was associated with lower likelihood of being in the lowest quartile of TTR. Finally, lower adherence was associated with increased likelihood of having poor TTR (Table). Conclusions: TTR to Warfarin in this underserved population is suboptimal. Given that adherence to Warfarin is independently associated with poor TTR, in the absence of strong adherence interventions, a policy of universal NOAC adoption is unlikely to significantly improve outcomes. If patients are transitioned to NOACs, this data implies that a targeted adherence intervention will be necessary to ensure that the medication is effective in reducing the risk of stroke.

Solving endogenous regime switching models

This paper solves rational expectations models in which structural parameters switch across multiple regimes according to state-dependent (endogenous) transition probabilities. Assuming small shocks and smooth transition probabilities, we apply a perturbation approach. We first provide for conditions under which a unique bounded equilibrium exists. We then compute first- and second-order approximations. In a new-Keynesian model with monetary policy switching, we document new effects of monetary policy switching when transition probabilities depend on inflation.

Transmission network switching for reducing market power cost in generation sector: A Nash-equilibrium approach

The transmission network switching is proposed in the literature as a way to improve social welfare in liberalized power markets. 〈7〉 Moreover, exercise of market power by strategic generating companies (Gencos) causes some extra cost in electricity market which can be alleviated by implementing appropriate switching policies. This paper contributes to the existing literature by developing a mathematical model that explores, from an economic perspective, the transmission network switching in the context of market power. The strategic Gecnos are modelled based on the Cournot game. The Nash equilibrium of the game between Gencos is formulated as an equilibrium problem with equilibrium constraint (EPEC). The EPEC problem is transformed to a mixed-integer linear feasibility problem. To handle the multiple-Nash-equilibria situations, the solution concept of the extremal-Nash equilibrium (ENE) is introduced. A mixed-integer linear program (MILP) is derived for finding ENE. The transmission switching decisions are modelled as binary variables controlled by the system operator (TSO). The TSO minimizes the system dispatch cost calculated at ENE and network reconfiguration cost. The TSO minimizes the cost using its transmission switching decisions. The problem faced by the TSO is a mixed-integer bilevel linear program (MIBLP) with binary variables in both upper and lower levels. The upper level models the TSO's action and the lower level the oligopolistic Gencos (competing in Cournot game). A (parallel) branch-and-bound technique is used to solve the developed MIBLP model. An illustrative 3-bus example system and the IEEE-RTS96 are modelled and carefully studied. 〈8〉The numerical results demonstrate that: 1 – the (parallel) branch-and-bound technique can effectively solve the developed MIBLP, 2 – using the developed model, the system operator can change topology of the network by switching the lines in order to reduce the adverse effect of the strategic behaviour of Gecnos.

解題:主要水田地帯における農業構造の変動とその行方 ─農政転換，低米価下における担い手形成と農地利用の動き─

解題:主要水田地帯における農業構造の変動とその行方 ─農政転換，低米価下における担い手形成と農地利用の動き─

Controlling Inflation with Switching Monetary and Fiscal Policies: Expectations, Fiscal Guidance and Timid Regime Changes

Inflation depends on both monetary and fiscal policies and on how agents believe that these policies will evolve in the future. Can monetary policy control inflation, when both monetary and fiscal policies are allowed to change over time? To analyse this problem, we study a model in which both monetary and fiscal policies may switch according to a Markov process. Controlling inflation entails a unique and Ricardian solution. We propose a natural generalisation of the original Leeper (1991) taxonomy, introducing the concepts of globally active (or passive) and globally switching policies to define the conditions that allow monetary policy to control inflation under Markov switching. First, monetary and fiscal policies need to be globally balanced to guarantee a unique equilibrium: globally active monetary policies need to be coupled with globally passive fiscal policies, and switching monetary policies with switching fiscal policies. Second, this distinction characterises the nature of the solutions: a globally AM/PF regime is Ricardian, while a globally switching regime features expectation and wealth effects. Third, the strength of policy deviations across regimes is key, insofar a globally active (or passive) policy allows only timid deviations. Finally, our framework can rationalise the impulse responses from a Bayesian VAR on U.S. data for the recent zero lower bound period as being due to timidity in fiscal actions that have been unable to spur inflation.

A Dynamic Switching Policy with Combined Make-to-Stock/Make-to-Order Thresholds for Hybrid Production Systems

AbstractDynamic MTS/MTO hybrid production systems [1]; in which some of machines, called hybrid machines which can be switched between make-to-stock (MTS) and make-to-order (MTO) production, are superior for enhancing utilization of machines, but they increase MTS inventory and MTO waiting customers. In this paper, in order to improve productivity, we propose a switching policy with combined thresholds in which both of MTS inventory level and MTO waiting customer level are utilized for switching decision. This performance is analyzed based on Markov analysis with the state transition diagram. The results of numerical experiments under several scenarios show the effectiveness of the proposed policy.

Airline switching revenue with price-guarantees

Many airlines permit ticket holders to change the time of their flight by paying a switching fee. For an airline, selecting a switching fee is an important strategic decision for two reasons. First, it is a supplementary but considerable revenue item for firms with a narrow profit margin. Second, the fee impacts their demand and consequently their capacity planning. Knowing that a low or high fee could cause operational challenges, such as unsold capacity or lost sales, the question that arises is what fee should be set for switching. We model a single firm which delivers two sequential homogeneous services that are priced differently; a high-priced service followed by a low-priced one. The price difference triggers a demand leakage across the two services. Switching customers pay a switching fee but get reimbursed the price difference. This reimbursement is an extension of airlines’ current switching practice and money-back guarantees that are common in retail industries (such as consumer electronics). We analyze the firm’s revenue function and derive the optimal switching fee. We show that the variability in switching behavior of customers drives the firm’s ideal switching policy. When this uncertainty increases, the firm should impose a higher switching fee. Furthermore, the optimal switching fee is rising in the resources’ prices. Finally, through numerical analysis, we investigate the joint decisions of the service price and the switching fee. This analysis shows that the optimal fee is increasing in the size of the low-price service.

Routing, Modulation Format, Baud Rate and Spectrum Allocation in Optical Metro Rings With Flexible Grid and Few-Mode Transmission

Application of few-mode transmission (FMT) in transport optical network is currently under scrutiny, especially for metro networks, where shorter distances and pressing traffic increase (e.g., due to a growing need for metro datacenter interconnection) represent promising conditions for FMT deployment. In this paper, we analyze, from a network-level perspective, the benefits introduced by FMT in metro networks. We consider the application in a flexi-grid network of a FMT system employing hybrid optical/digital mode demultiplexer and low-complexity MIMO-based digital signal processing (DSP). Under this system model, we derive the reach values associated to different modulation formats, baud rates, and number of modes. For the first time to the best of our knowledge, we formulate using linear programming the routing, modulation format, baud rate, and mode assignment problem, for two different switching policies (spatially flexible and spatially and spectrally flexible switching). Using our proposed modes, we identify the configurations that ensure minimum spectrum occupation or minimum cost of installed transceivers, and contrast them to the benchmark case of single-mode transmission.

Power Splitting-Based SWIPT With Decode-and-Forward Full-Duplex Relaying

This paper investigates simultaneous wireless information and power transfer (SWIPT) for a decode-and-forward (DF) full-duplex relay (FDR) network. A battery group consisting of two batteries is applied to utilize the relay-harvested energy for FDR transmission. The virtual harvest-use model and the harvest-use-store model are considered, respectively. By switching between two batteries for charging and discharging with the aid of power splitting (PS), concurrent source and relay transmissions can overcome spectral efficiency loss compared with half-duplex relay (HDR)-assisted PS-SWIPT. The outage probability for the virtual harvest-use model is presented in an exact integral form and the optimal PS (OPS) ratio that maximizes the end-to-end signal-to-interference-plus-noise ratio (e-SINR) is characterized in closed form via the cubic formula. The fundamental tradeoff between the e-SINR and recycled self-power is quantified. The OPS ratios and the corresponding outage probabilities in noise-limited and interference-limited environments are also derived. In the harvest-use-store model, a greedy switching (GS) policy is implemented with energy accumulation across transmission blocks. The OPS ratio of the GS policy is presented and the corresponding outage probability is derived by modeling the relay’s energy levels as a Markov chain with a two-stage state transition. Numerical results verify the performance improvement of the proposed scheme over HDR-assisted PS-SWIPT in terms of outage probability and average throughput.

PHP128 - Bio-Similar Or Different? – Understanding The Payer Perspective

Although generic substitution has largely been accepted as desirable, the prescribing of biosimilars remains contentious. Biosimilar market penetration is expanding leading to a growing need to understand how this will affect global pharmaceutical markets. The objectives of the study were to provide insights into (1) payers’ perceptions towards biosimilar products and how the landscape will evolve in the coming years (2) payer expectations on the pricing of biosimilars and the impact on reference products (3) barriers to uptake and potential differences in attitudes between clinicians and payers. A 10 question online semi-quantitative survey was conducted which covered 9 markets: the UK, Germany, France, Netherlands, Sweden, Spain, Poland, Russia, and the US. The participants selected for the survey hold or have held senior positions within their respective country payer organisations. The research showed that 7 out of 9 analysed markets have or plan to implement an active policy of switching to biosimilars. Cost difference between a biosimilar and a reference product was chosen as the most important factor in payer decision-making by 100% responders. The current level of discount for biosimilars compared to reference products varied across the studied markets (range 10-40%). The potential for the introduction of a biosimilar to trigger price negotiations was inconsistent across markets, although there was an acknowledged impact on the price of the original brand (range 0-40%). 8 out of 9 responders anticipated the market share for biosimilars to be >25% in the next 5 years with oncology and immunology the most desirable areas for biosimilar penetration. The study has demonstrated a wide-variation in how markets approach biosimilar products; however, there are clearly signs of convergence in payer thinking as biosimilar usage expands. Respondents highlighted clinical advocacy and defensive approaches from reference product manufacturers as the main barriers to biosimilar uptake.

Global Determinacy Under Monetary and Fiscal Policy Switchings

This paper examines equilibrium determinacy in the context of a structural regime switching macro model with monetary and fiscal policy switching. We first show theoretically and in practice that the long-run Taylor principle proposed by Davig and Leeper (2007) is necessary but not sufficient for determinacy in mean-square stability sense. We then show that stochastic switching in policy stances substantially changes the determinacy region. On the one hand, a unique stable equilibrium under regime switching may exist when monetary and fiscal policies are both recurrently passive or active. On the other hand, a switch between two alternative policy combinations which imply determinacy under two fixed-regimes often requires a large swing in fiscal policy in order to achieve global determinacy, ruling out some traditionally determinate equilibria. Finally, we show that money growth management can be an alternative to active fiscal policy in a zero lower-bound scenario in order to lead the economy to global determinacy.

Monetary and fiscal policy switching with time-varying volatilities

This paper extends the ongoing literature on regime change. The extension allows time variation in disturbance variances of interest rate rules for monetary policy and tax rules for fiscal policy that switch stochastically between two regimes. We achieve superior modelings of monetary and fiscal policy rules with quarterly US data.

Energy-Aware Adaptive Attitude Estimation Under External Acceleration for Pedestrian Navigation

In this paper, we consider the problem of a rigid body attitude estimation under external acceleration using a small inertial/magnetic sensors module containing a triad of gyroscope, accelerometer, and magnetometer. This paper is focused on two main challenges. The first one concerns the attitude estimation during dynamic cases, in which external acceleration occurs. In order to compensate for such external acceleration, we design a quaternion-based adaptive Kalman filter q-AKF. Precisely, a smart detector is designed to decide whether the body is in static or dynamic case. Then, the covariance matrix of the external acceleration is estimated to tune the filter gain. The second challenge is related to the energy consumption issue of gyroscope. In order to ensure a longer battery life for the inertial measurement units, we study the way to reduce the gyro measurements acquisition by switching on/off the sensor while maintaining an acceptable attitude estimation. The switching policy is based on the designed detector. The efficiency of the proposed scheme is evaluated by means of numerical simulations and experimental tests.

Valuation under uncertain energy prices and load demands of micro-CHP plants supplemented by optimally switched thermal energy storage

This paper aims at providing insight on the ability that thermal energy storage (TES) systems have to reduce the cost of operating CHP plants, when an optimal switching policy is adopted to regulate the storage level under uncertain market conditions and also uncertain load demands.To achieve this goal, this paper first proposes an efficient program to determine such an optimal policy, conceptually in line with the energy arbitrage capabilities attributed to electrical energy storage. The proposed algorithm is based on dynamic programming to cope with the stochastic nature of the problem in a Monte Carlo framework, while still keeping down its dimensionality. In addition, it is structured around simple manipulations of third-order tensors, which demonstrate to be effective in accelerating the speed of convergence.The program has been thereafter applied to a case analysis, based on a gas microturbine (MT) powering a small-size CHP plant, with associated TES and peak boiler; with a detailed formulation of the efficiency deterioration of the system at part-load operation. The optimal switching policy ensuing from solving the problem by means of the proposed algorithm shows to be strongly dependent on the plant layout. Additionally, the efficiency deterioration, as well as the existence of operation thresholds because of increased pollutant emissions, relevantly affect the optimal switching policy. An interpretation of the reasons why this occurs, along with a characterization, is provided based on the results yielded by the algorithm. Finally, a sensitivity analysis of the cost of operating the plant under different assumptions leads to a discussion about the optimal and threshold sizes of the MT and the TES.

A comparative cross-regime analysis on the performance of GARCH-based value-at-risk models: Evidence from the Johannesburg stock exchange

A topic of recent interest in financial risk management is the predictive accuracy of Value-at-risk (VaR) models for adequate capitalization under different market conditions (or regimes). This article assesses the forecasting performance of popular GARCH-based volatility models in the context of VaR estimation. In particular, we conduct a cross-regime analysis between time periods whereby market conditions experiences a shift. Stock returns data from the FTSE/JSE Africa All Share index were selected for the evaluation of both long and short positions of trade. Despite prior findings of the long memory models dominating in the South African financial market, we conclude that such dominance does not necessary hold when assessed under different regimes of the market. Moreover, our findings indicated a need for implementations of model switching policies, which may provide significant improvements in forecasting and minimize chances of VaR estimates falling short of actual trading losses.

Examining monetary policy reaction in the People’s Republic of China – a Markov switching policy index approach

This paper estimates a monetary policy rule for the People’s Republic of China (PRC) using a standard OLS estimation and a Markov switching model. As the People’s Bank of China (PBOC) generally uses a battery of instruments in the conduct of its monetary policy, these models are estimated using a constructed monetary policy index (MPI) in place of the traditional interest rate. This allows for a better understanding of the role the PBOC has played in the PRC’s unprecedented economic growth and its relatively low inflation over the last twenty years. This paper will not only examine the unique characteristics of Chinese monetary policy but may also give a more general insight into the dynamics of monetary policy reactions in other emerging markets and economies in transition.

Markov Decision Process-Based Switching Algorithm for Sustainable Rechargeable Wireless Sensor Networks

In a tree-based wireless sensor network (WSN), a tree structure rooted at sink node is usually created for efficient data collection. Recently, the use of solar harvesting technologies for rechargeable sensor nodes is evolving. Moreover, in a tree-based rechargeable WSN, the nodes that belong to different routes will have different energy dissipation due to unequal harvested-energy and utilized-energy. Network sustainability and energy efficiency are important issues in a tree-based rechargeable sensor network. In this paper, a Markov decision process-based switching algorithm has been designed for a sustainable data collection tree while reducing energy consumption in the network. Furthermore, an analysis of energy consumption has been performed using a real-time sensor traffic pattern. A prediction model has been adopted to estimate the harvesting energy (based on solar power) for the rechargeable sensor nodes. In this paper, the state of each node is defined based on different independent energy levels. The state of each node may change with time depending on harvested-energy and utilized-energy. The proposed Markov decision process approach finds the optimal switching policy for sensor nodes, which switch from one parent to another based on energy levels to preserve sustainability. A detailed theoretical analysis has been performed along with simulation results to show the efficacy of the proposed approach.

Repatriation taxes and outbound M&As

Repatriation taxes reduce the competitiveness of multinational firms from tax credit countries when bidding for targets in low tax countries. This comparative disadvantage with respect to bidders from exemption countries violates ownership neutrality, which results in production inefficiencies due to second-best ownership structures. This paper empirically estimates the magnitude of these effects. The abolishment of repatriation taxes in Japan and in the U.K. in 2009 has increased the number of acquisitions abroad by Japanese and British firms by 16.1% and 1.6%, respectively. A similar policy switch in the U.S. is simulated to increase the number of U.S. cross-border acquisition by 11.0%. The yearly gain in efficiency is estimated to be 108.9 million dollar due to the Japanese reform and 3.9 million dollar due to the U.K. reform. Simulating such a reform for the U.S. results in a yearly efficiency gain of 537.0 million dollar.