A re-examination of value-creation through strategic alliances

This paper uses a sample of 335 firms participating in strategic alliances in order to re-examine the value creation through strategic alliances. We show that the immediate positive response of stock markets to new strategic alliances is followed by negative abnormal returns. Twenty days after announcements, cumulative positive abnormal return is only evident for the firms with the highest stock market’s response to the announcement. We relate the positive abnormal returns reported in previous research to the presence of short-run over-reaction in stock markets and conclude in the market’s ability to identify the more valuable alliances.Strategic alliance; over-reaction; momentum

Design and Performance of Thermal Energy Storage Module using High Thermal Conductivity Phase Change Composite Material

HVAC (Heating, Ventilation and Cooling) accounts for approximately 15-30% of a commercial building’s electricity cost and about 20-40% of electricity consumption. Electricity costs charged by the utilities companies for commercial building customers includes consumption charges ($/kWh) and demand charges ($/kW) depending on the time of use (TOU) charges. Thus, there is great interest to reduce the electricity consumption charges and demand charges by using new energy efficient technologies and products. One such product is a thermal energy storage (TES) system using a phase change material (PCM) to offset the cooling costs associated with air-conditioning systems by reducing the electricity consumption during peak time periods. A patented phase change composite (PCC) TES material was developed that has high thermal conductivity and adjustable phase change temperature. Compared to ice, the PCC TES system is capable of higher heat transfer rate and has lower system and operational costs. Proof of concept demonstration and working prototype results of a PCC TES system were successfully completed. Results show that a PCC TES system can be designed for a commercial building and maintain high efficiency with either low or high discharge rates. Techno-economic analysis for peak shaving or peak load shifting of a commercial air-conditioning system was studied, comparing Ice and PCC TES system. Results show that a PCC TES system can compete with Ice TES system with favorable ROI (return on investment).

New Copper-based Heat Exchangers for Alternative Refrigerants

The ongoing global effort to replace current refrigerants with zero Ozone Depletion Potential (ODP) and virtually zero Global Warming Potential (GWP) refrigerants has important implications for heat exchangers, air conditioning system design, and the materials choices in these designs. Natural refrigerants with higher flammability, CO2, new HFC blends, and new HFO’s each place different requirements on the heat exchanger design, whether it be for higher equipment efficiency, to reduce refrigerant charge, to operate to much higher operating pressures or temperatures, to prevent corrosion or to avoid leakage. This paper presents critical information that engineers need to know about how heat exchangers based on round inner-grooved small-diameter copper Microgroove™ tube and newly-developed flat copper microchannel tube can be applied in air conditioning equipment using new alternative refrigerants. Heat exchangers based on Microgroove™ tubes with 5mm or 4mm diameter provide solutions for new refrigerants. For example, Microgroove™ tube systems have been found to provide a proven and safe solution for air conditioners using new refrigerant R290 (propane). They permit significantly smaller refrigerant charge, equivalent to those used in microchannel extrusions, while providing reduced manufacturing complexity and maintaining energy efficiency similar to traditional units. These tubes have antimicrobial properties that eliminate mold growth. They have a high level of solution flexibility to provide special circuiting or enlarged coils and eliminate over-sizing for standard products. Thin wall Copper microchannel extruded tubes exhibit high burst pressure at post-brazed conditions. These tubes are especially attractive for use at the high operating temperature and pressure associated with R744 systems. Heat exchangers constructed with such tubes maintain their post braze strength and burst pressure resistance at 180°C operating temperature, have high thermal conductivity, and thus maintain a small heat exchanger size. In addition, microchannel tube produced with a copper alloy such as brass provides the additional benefits of lower cost, corrosion resistance and higher material strength that can lead to even thinner walls and reduced heat exchanger size. Examples of heat exchangers made using copper microchannel extruded tubes fabricated using Cuprobraze technology are provided in this paper. In the quest to improve the environmental performance of air conditioning systems, it is critical to examine the total Life Cycle Climate Performance (LCCP) including the effects of the refrigerant choice and the effect of energy use across the system life cycle. All-copper heat exchangers using either copper Microgroove™ or microchannel tubes suppress the growth of bacteria and mold that reduce system energy efficiency, cause product deterioration and foul odors. Mold growth studies show aluminum fin heat exchanger performance decreases up to 20% after four years of operation, where mold growth covered 60% of the fin surface. These new copper-based solutions provide an added protection against longer term potential efficiency losses in systems using new refrigerants. They are appropriate for use in air conditioning systems that achieve the highest level of Life Cycle Climate Performance

PIP: Positional-encoding Image Prior

In Deep Image Prior (DIP), a Convolutional Neural Network (CNN) is fitted to map a latent space to a degraded (e.g. noisy) image but in the process learns to reconstruct the clean image. This phenomenon is attributed to CNN's internal image-prior. We revisit the DIP framework, examining it from the perspective of a neural implicit representation. Motivated by this perspective, we replace the random or learned latent with Fourier-Features (Positional Encoding). We show that thanks to the Fourier features properties, we can replace the convolution layers with simple pixel-level MLPs. We name this scheme ``Positional Encoding Image Prior" (PIP) and exhibit that it performs very similarly to DIP on various image-reconstruction tasks with much less parameters required. Additionally, we demonstrate that PIP can be easily extended to videos, where 3D-DIP struggles and suffers from instability. Code and additional examples for all tasks, including videos, are available on the project page https://nimrodshabtay.github.io/PIP

No Polynomial Kernels for Knapsack

This paper focuses on kernelization algorithms for the fundamental Knapsack problem. A kernelization algorithm (or kernel) is a polynomial-time reduction from a problem onto itself, where the output size is bounded by a function of some problem-specific parameter. Such algorithms provide a theoretical model for data reduction and preprocessing and are central in the area of parameterized complexity. In this way, a kernel for Knapsack for some parameter $k$ reduces any instance of Knapsack to an equivalent instance of size at most $f(k)$ in polynomial time, for some computable function $f(\cdot)$. When $f(k)=k^{O(1)}$ then we call such a reduction a polynomial kernel. Our study focuses on two natural parameters for Knapsack: The number of different item weights $w_{\#}$, and the number of different item profits $p_{\#}$. Our main technical contribution is a proof showing that Knapsack does not admit a polynomial kernel for any of these two parameters under standard complexity-theoretic assumptions. Our proof discovers an elaborate application of the standard kernelization lower bound framework, and develops along the way novel ideas that should be useful for other problems as well. We complement our lower bounds by showing the Knapsack admits a polynomial kernel for the combined parameter $w_{\#}+p_{\#}$