Seasonal predictability of the winter NAO from north Atlantic sea surface temperatures

[1] We examine the seasonal predictability of the winter (December-January-February) North Atlantic Oscillation (NAO) from lagged north Atlantic sea surface temperatures (SSTs) for the period 1950/1-2000/1. We identify two lagged modes of SST variability whose principal components (PCs) are correlated significantly to upcoming winter NAO indices. We use linear regression with the PCs as predictors to assess the predictability of the winter NAO from cross-validation over the full period and from replicated real-time forecasts over the recent 15 year period 1986/7-2000/1. The model anticipates, in early November, the upcoming winter NAO - for a range of NAO indices - with a correlation between 0.47 and 0.63 for 1950/ 1-2000/1, and between 0.51 and 0.65 for the replicated real-time forecast period. The model also anticipates the correct NAO sign in 67% to 75% of the last 51 winters and in 80% to 93% of the last 15 winters

Etalon Array Reconstructive Spectrometry.

Compact spectrometers are crucial in areas where size and weight may need to be minimized. These types of spectrometers often contain no moving parts, which makes for an instrument that can be highly durable. With the recent proliferation in low-cost and high-resolution cameras, camera-based spectrometry methods have the potential to make portable spectrometers small, ubiquitous, and cheap. Here, we demonstrate a novel method for compact spectrometry that uses an array of etalons to perform spectral encoding, and uses a reconstruction algorithm to recover the incident spectrum. This spectrometer has the unique capability for both high resolution and a large working bandwidth without sacrificing sensitivity, and we anticipate that its simplicity makes it an excellent candidate whenever a compact, robust, and flexible spectrometry solution is needed

China’s Electricity Market Reform and Power Plants Efficiency

In the past three decades, Chinese electricity industry has experienced a series of regulatory reforms serving different purposes at different stages. In 2002, the former vertically integrated electricity utility - the State Power Corporation (SPC) – was divested and the generation sector was separated from the transmission and distribution networks in an effort to improve production efficiency. In this paper we study the impact of the reform on efficiency of fossil-fired power plants using plant-level data during 2000-2008. Our results from the data envelopment analysis (DEA) and panel regressions show that: 1) the total factor productivity (TFP) growth mainly comes from technological change; 2) the technical efficiency of previously SPC-managed power plants is converging to that of better-performing independent power producers (IPPs); 3) capacity utilization and unit size are significant factors affecting changes in technical efficiency and the pattern of converging technical efficiency between the two kinds of power plants; 4) most plants operate at increasing returns to scale indicating further cost savings could be achieved through increasing output.Efficiency, DEA, Malmquist Index, China, Electricity, Industrial Organization, Productivity Analysis, Resource /Energy Economics and Policy, D24, L11, L51, L94, L98,

Time and Location Aware Mobile Data Pricing

Mobile users' correlated mobility and data consumption patterns often lead to severe cellular network congestion in peak hours and hot spots. This paper presents an optimal design of time and location aware mobile data pricing, which incentivizes users to smooth traffic and reduce network congestion. We derive the optimal pricing scheme through analyzing a two-stage decision process, where the operator determines the time and location aware prices by minimizing his total cost in Stage I, and each mobile user schedules his mobile traffic by maximizing his payoff (i.e., utility minus payment) in Stage II. We formulate the two-stage decision problem as a bilevel optimization problem, and propose a derivative-free algorithm to solve the problem for any increasing concave user utility functions. We further develop low complexity algorithms for the commonly used logarithmic and linear utility functions. The optimal pricing scheme ensures a win-win situation for the operator and users. Simulations show that the operator can reduce the cost by up to 97.52% in the logarithmic utility case and 98.70% in the linear utility case, and users can increase their payoff by up to 79.69% and 106.10% for the two types of utilities, respectively, comparing with a time and location independent pricing benchmark. Our study suggests that the operator should provide price discounts at less crowded time slots and locations, and the discounts need to be significant when the operator's cost of provisioning excessive traffic is high or users' willingness to delay traffic is low.Comment: This manuscript serves as the online technical report of the article accepted by IEEE Transactions on Mobile Computin

Tri-meson bound state BBB∗BBB^{\ast} via delocalized π\pi~Bond

During the last decades, numerous exotic states which cannot be explained by the conventional quark model have been observed in experiment. Some of them can be understood as two-body hadronic molecules, such as the famous $X(3872)$, analogous to deuteron in nuclear physics. Along the same line, the existence of the triton leaves an open question whether there is a bound state formed by three hadrons. Since, for a given potential, a system with large reduced masses is more easier to form a bound state, we study the $BBB^{\ast}$ system with the one-pion exchange potential as an exploratory step by solving the three-body Schr\"odinger Equation. We predict that a tri-meson molecular state for the $BBB^{\ast}$ system is probably existent as long as the molecular states of its two-body subsystem $BB^*$ exist.Comment: 20 pages, 20 figure