Stepwise Green Investment under Policy Uncertainty

We analyse how market price and policy uncertainty, in the form of random provision or retraction of a subsidy, interact to affect the optimal time of investment and the size of a renewable energy (RE) project that can be completed in either a single (lumpy investment) or multiple stages (stepwise investment). The subsidy takes the form of a fixed premium on top of the electricity price, and, therefore, investment is subject to electricity price uncertainty. We show that the risk of a permanent retraction (provision) of a subsidy increases (decreases) the incentive to invest, yet lowers (raises) the amount of installed capacity, and that this result is more pronounced as the size of the subsidy increases. Additionally, we show that increasing the number of policy interventions lowers the expected value of a subsidy and the size of the project. Furthermore, we illustrate that, although an increase in the size of a subsidy lowers the relative value of the stepwise investment strategy, the expected value of a lumpy investment strategy is still lower than that of stepwise investment

Sequential investment in renewable energy technologies under policy uncertainty

Although innovation and support schemes are among the main forces that drive investment in renewable energy (RE) technologies, both involve considerable uncertainty. We develop a real options framework to analyse the impact of technological, policy and electricity price uncertainty on the decision to invest sequentially in successively improved versions of a RE technology. Technological uncertainty is reflected in the random arrival of innovations, and policy uncertainty in the likely provision or retraction of a subsidy that takes the form of a fixed premium on top of the electricity price. We show that greater likelihood of subsidy retraction (provision) lowers (raises) the incentive to invest, and, by comparing a stepwise to a lumpy investment strategy, we show how an embedded option to adopt an improved technology version mitigates the impact of subsidy retraction on investment timing. Specifically, we show how stepwise investment facilitates earlier technology adoption compared to lumpy investment, and that, under stepwise investment, technological uncertainty accelerates technology adoption, thus further offsetting the incentive to delay investment in the light of subsidy retraction

Optimal regime switching under risk aversion and uncertainty

echnology adoption is key for corporate strategy, often determining the success or failure of a company as a whole. However, risk aversion often raises the reluctance to make a timely technology switch, particularly when this entails the abandonment of an existing market regime and entry in a new one. Consequently, which strategy is most suitable and the optimal timing of regime switch depends not only on market factors, such as the definition of the market regimes, as well as economic and technological uncertainty, but also on attitudes towards risk. Therefore, we develop a utility-based, regime-switching framework for evaluating different technology-adoption strategies under price and technological uncertainty. We assume that a decisionmaker may invest in each technology that becomes available (compulsive) or delay investment until a new technology arrives and then invest in either the older (laggard) or the newer technology (leapfrog). Our results indicate that, if market regimes are asymmetric, then greater risk aversion and price uncertainty in a new regime may accelerate regime switching. In addition, the feasibility of a laggard strategy decreases (increases) as price uncertainty in an existing (new) regime increases. Finally, although risk aversion typically favours a compulsive and a laggard strategy, a leapfrog strategy may be feasible under risk aversion provided that the output price and the rate of innovation are sufficiently high

Police Misconduct, Community Opposition, and Urban Governance in New York City, 1945–1965

In the post–World War II period, the police department emerged as one of the most problematic municipal agencies in New York City. Patrolmen and their superiors did not pay much attention to crime; instead they looked the other way, received payoffs from organized crime, performed haphazardly, and tolerated conditions that were unacceptable in a modern city with global ambitions. At the same time, patrolmen demanded deference and respect from African American civilians and routinely demeaned and brutalized individuals who appeared to be challenging their authority. The antagonism between African Americans and the New York Police Department (NYPD) intensified as local and national black freedom organizations paid more attention to police behavior and made police reform one of their main goals

Wave propagation in pressurised composite structures with frequency band gap behaviour

In engineering there are numerous examples of structures, such as train rails and airplane fuselages, that present periodicity in their geometry or mechanical properties. It has been observed that this periodicity leads to banded frequency response after excitation. These band gaps can be engineered to isolate noise and vibrations of the periodic structure. In this paper an infinite composite sandwich beam with hollow and pressurised core cells as periodic band gap inducing factors was examined. Wave finite element (WFE) method was used to predict the effect of pressured core cells periodicity on wave propagation and band gaps generation. Three low order finite elements (FE) models were produced using commercially available FE software package. These models consisted of a small section of the simple sandwich beam with homogenous core, with hollow core and with pressurised hollow core

Wave steering effects in anisotropic composite structures: direct calculation of the energy skew angle through a finite element scheme

A systematic expression quantifying the wave energy skewing phenomenon as a function of the mechanical characteristics of a non-isotropic structure is derived in this study. A structure of arbitrary anisotropy, layering and geometric complexity is modelled through Finite Elements (FEs) coupled to a periodic structure wave scheme. A generic approach for efficiently computing the angular sensitivity of the wave slowness for each wave type, direction and frequency is presented. The approach does not involve any finite differentiation scheme and is therefore computationally efficient and not prone to the associated numerical errors

Performance Optimization and Parallelization of a Parabolic Equation Solver in Computational Ocean Acoustics on Modern Many-core Computer

As one of open-source codes widely used in computational ocean acoustics, FOR3D can provide a very good estimate for underwater acoustic propagation. In this paper, we propose a performance optimization and parallelization to speed up the running of FOR3D. We utilized a variety of methods to enhance the entire performance, such as using a multi-threaded programming model to exploit the potential capability of the many-core node of high-performance computing (HPC) system, tuning compile options, using efficient tuned mathematical library and utilizing vectorization optimization instruction. In addition, we extended the application from single-frequency calculation to multi-frequency calculation successfully by using OpenMP+MPI hybrid programming techniques on the mainstream HPC platform. A detailed performance evaluation was performed and the results showed that the proposed parallelization obtained good accelerated effect of 25.77X when testing a typical three-dimensional medium-sized case on Tianhe-2 supercomputer. It also showed that the tuned parallel version has a weak-scalability. The speed of calculation of underwater sound field can be greatly improved by the strategy mentioned in this paper. The method used in this paper is not only applicable to other similar computing models in computational ocean acoustics but also a guideline of performance enhancement for scientific and engineering application running on modern many-core-computing platform.Comment: 9 pages, 8 figures, 3 tables. preprint for the International Conference on Computer Science and Application Engineering (CSAE2017). 2017.10.21-23, Shanghai, Chin