Performance Characteristics of a Refrigerator-Freezer with Parallel Evaporators using a Linear Compressor

A linear compressor for a domestic refrigerator-freezer has energy saving potential compared with a reciprocating compressor because of a low friction loss and free piston system. A linear compressor can control the piston stroke since it does not have mechanical restriction of piston movement. Therefore, the energy consumption of a domestic refrigerator-freezer using a linear compressor can be reduced by changing the cooling capacity of the compressor. In order to investigate the performance of a refrigerator-freezer with parallel evaporators using a linear compressor and the relation between cooling capacity of the linear compressor and cooling load, experimental simulation is conducted with variation of the capacity of a linear compressor, an ambient temperature, and cooling load. In addition, the power consumption of a linear compressor is compared to that of an inverter reciprocating compressor in a refrigerator-freezer. The performance of a linear compressor is measured with variation of the capacity of a linear compressor from 60% to 100% of the maximum capacity in a refrigerator-freezer. Based on the experimental data, the power consumption of a linear compressor is reduced by 22.4% with 70% capacity compared to 100% but on-time ratio is increased by 12.8%

Valuation of Exchange Option with Credit Risk in a Hybrid Model

In this paper, the valuation of the exchange option with credit risk under a hybrid credit risk model is investigated. In order to build the hybrid model, we consider both the reduced-form model and the structural model. We adopt the probabilistic approach to derive the closed-form formula of an exchange option price with credit risk under the proposed model. Specifically, the change of measure technique is used repeatedly, and the pricing formula is provided as the standard normal cumulative distribution functions

Variational inequality arising from variable annuity with mean reversion environment

Abstract In this paper, we study a variational inequality arising from variable annuity (VA) to find the optimal surrender strategy for a VA investor when the underlying asset follows a mean reverting process. We formulate the problem as a free boundary partial differential equation (PDE) to obtain the optimal strategy. The PDE is solved analytically by the Mellin transform approach. Using the Mellin transform, we derive the integral equations for the value of the VA and the optimal surrender boundary. Since the solutions are obtained as the integral equations, we use the recursive integration method to determine the optimal surrender strategy. Finally, we provide the optimal surrender boundaries and values of VA with respect to some significant parameters to show the impacts of mean reversion

Efficient Lattice Method for Valuing of Options with Barrier in a Regime Switching Model

We propose an efficient lattice method for valuation of options with barrier in a regime switching model. Specifically, we extend the trinomial tree method of Yuen and Yang (2010) by calculating the local average of prices near a node of the lattice. The proposed method reduces oscillations of the lattice method for pricing barrier options and improves the convergence speed. Finally, computational results for the valuation of options with barrier show that the proposed method with interpolation is more efficient than the other tree methods

Low-Cost Implementation of a Named Entity Recognition System for Voice-Activated Human-Appliance Interfaces in a Smart Home

When we develop voice-activated human-appliance interface systems in smart homes, named entity recognition (NER) is an essential tool for extracting execution targets from natural language commands. Previous studies on NER systems generally include supervised machine-learning methods that require a substantial amount of human-annotated training corpus. In the smart home environment, categories of named entities should be defined according to voice-activated devices (e.g., food names for refrigerators and song titles for music players). The previous machine-learning methods make it difficult to change categories of named entities because a large amount of the training corpus should be newly constructed by hand. To address this problem, we present a semi-supervised NER system to minimize the time-consuming and labor-intensive task of constructing the training corpus. Our system uses distant supervision methods with two kinds of auto-labeling processes: auto-labeling based on heuristic rules for single-class named entity corpus generation and auto-labeling based on a pre-trained single-class NER model for multi-class named entity corpus generation. Then, our system improves NER accuracy by using a bagging-based active learning method. In our experiments that included a generic domain that featured 11 named entity classes and a context-specific domain about baseball that featured 21 named entity classes, our system demonstrated good performances in both domains, with F1-measures of 0.777 and 0.958, respectively. Since our system was built from a relatively small human-annotated training corpus, we believe it is a viable alternative to current NER systems in smart home environments

Analytic Valuation Formula for American Strangle Option in the Mean-Reversion Environment

This paper investigates the American strangle option in a mean-reversion environment. When the underlying asset follows a mean-reverting lognormal process, an analytic pricing formula for an American strangle option is explicitly provided. To present the pricing formula, we consider the partial differential equation (PDE) for American strangle options with two optimal stopping boundaries and use Mellin transform techniques to derive the integral equation representation formula arising from the PDE. A Monte Carlo simulation is used as a benchmark to validate the formula’s accuracy and efficiency. In addition, the numerical examples are provided to demonstrate the effects of the mean-reversion on option prices and the characteristics of options with respect to several significant parameters