Miracle-dz/UniFAR-FTUs huggingface dataset:
Efficiency Enhancement in Organic Photovoltaic Cells: Consequences of Optimizing Series Resistance

Here, means to enhance power conversion efficiency (PCE or η) in bulk‐heterojunction (BHJ) organic photovoltaic (OPV) cells by optimizing the series resistance (Rs)—also known as the cell internal resistance—are studied. It is shown that current state‐of‐the‐art BHJ OPVs are approaching the limit for which efficiency can be improved via Rs reduction alone. This evaluation addresses OPVs based on a poly(3‐hexylthiophene):6,6‐phenyl C61‐butyric acid methyl ester (P3HT:PCBM) active layer, as well as future high‐efficiency OPVs (η > 10%). A diode‐based modeling approach is used to assess changes in Rs. Given that typical published P3HT:PCBM test cells have relatively small areas (∼0.1 cm2), the analysis is extended to consider efficiency losses for larger area cells and shows that the transparent anode conductivity is then the dominant materials parameter affecting Rs efficiency losses. A model is developed that uses cell sizes and anode conductivities to predict current–voltage response as a function of resistive losses. The results show that the losses due to Rs remain minimal until relatively large cell areas (>0.1 cm2) are employed. Finally, Rs effects on a projected high‐efficiency OPV scenario are assessed, based on the goal of cell efficiencies >10%. Here, Rs optimization effects remain modest; however, there are now more pronounced losses due to cell size, and it is shown how these losses can be mitigated by using higher conductivity anodes.
Why fi scal commitment improves price stabilization 1

We examine the relations between monetary and fiscal policies in the process of macroeconomic stabilization. Our model suggests that each policy maker prefers to be the second mover in a ”Stackelberg” situation, i.e. where one policy makers precommits its policy choice. At the same time, both Stackelberg solutions are preferable, for each policymaker, to the Nash solution. We argue that there is a natural way to choose among the two Stackelberg games, and that accordingly the government should act as the leader and adopt a fiscal policy rule based on the minimization of a loss function, which internalizes also the objective of price stability. This solution mirrors existing institutional arrangements, where fiscal policy decisions are typically taken before and less frequently than monetary policy decisions. We interpret our results in relation to the debate on monetary-fiscal coordination within countries that delegate monetary policy to an independent central bank. We also show that our results have relevant implications for tracing the source of fiscal policy disagreements in a monetary union with decentralized fiscal authorities.
Changes in hyperfrontality of cerebral blood flow and carbon dioxide reactivity with age.

We evaluated the topographic distributions of regional cerebral blood flow in 51 normal subjects (mean age 41 years) by the xenon-133 inhalation technique. Forty-five of these subjects were divided by age into young normals less than 30 years old (mean age 24 years), middle-aged normals 30-50 years old (mean age 40 years), and elderly normals greater than 50 years old (mean age 62 years); there were 15 subjects in each group. The distributions of vascular CO2 reactivity to hypocapnia were also evaluated in 20 of the normal subjects (mean age 34 years), including 11 younger normals less than 30 years old (mean age 24 years) and nine older (middle-aged or elderly) normals greater than or equal to 30 years old (mean age 45 years). The hyperfrontal distribution of regional cerebral blood flow observed in the young and middle-aged normals was not observed in the elderly normals. The hyperfrontal distribution of vascular CO2 reactivity observed in the younger normals was absent in the older normals. In addition, the correlation between regional cerebral blood flow and vascular CO2 reactivity observed in the younger normals was disturbed in the older normals. The data show a hyperfrontal distribution of regional cerebral blood flow in normal subjects that diminishes during the fifth and sixth decades, along with a distribution of vascular CO2 reactivity in younger normal subjects that is not homogeneous throughout the frontoparietal regions. (ABSTRACT TRUNCATED AT 250 WORDS)
Hypertensive Intracerebral Hemorrhage in Young People: Previously Unnoticed Age-Related Clinical Differences

Background and Purpose— Hypertensive intracerebral hemorrhage (ICH) in young people has been the object of only succinct analyses. Therefore, it is unclear whether extrapolation of the information obtained from older patients is also valid for the young. Here we describe young persons with hypertensive ICH and compare them with their older counterparts to determine whether age-related clinical differences exist. Methods— From 1988 to 2004, we studied 35 consecutive young patients with ICH (60% men; mean age, 33 years; range, 15 to 40 years) for whom the etiology of the brain hemorrhage was hypertension. For clinical comparisons, sex-matched persons with hypertensive ICH, aged >40 years, were randomly selected by a factor of 3:1 (n=105). Results— Essential hypertension was present in 26 (74%) young patients and secondary hypertension in 9 (26%), with renovascular hypertension being the most common cause (n=5, 55%). Compared with older patients, the young had higher blood pressures, smaller hemorrhage volumes, lower rates of ventricular extensions (for all, P<0.05), and different distribution pattern of ICHs (P=0.05), without cerebellar and lobar locations. Thirty-day mortality was markedly lower in the young than in older persons (P=0.001), nevertheless at the expense of more incapacitating disabilities. Conclusions— Young people presenting with hypertensive ICH differ in clinical characteristics and have a different prognosis when compared with their older counterparts. These findings suggest underlying age-related differences in disease pathogenesis.
A general framework for continuous time power control in time varying long term fading wireless networks

In this paper, a general framework for continuous time power control algorithm under time varying long term fading wireless channels is developed. This contrasts most of the power control algorithms introduced in the literature that assume power control takes place in discrete time intervals and can only be used as long as the time duration for successive adjustments of transmitter powers is less than the coherence time of the channel. In continuous time power control, there is no restriction on how fast the wireless channel is varying. Moreover, a sufficient condition for the existence of the optimal continuous time power is derived. The optimal continuous time power control algorithm is developed under time varying long term fading wireless channels, which are based on stochastic differential equations.
From Ticking to Clicking: Changes in Auditing Techniques in Britain from the 19th Century to the Present

The purpose of this article is to detail and explain the changes in auditing techniques that have taken place in Britain since the Victorian era, an area of study hitherto neglected by accounting historians. In so doing, it is hoped that an increasing knowledge of past practices will put the current processes into context. The source material for the paper includes new evidence from a program of oral history and postal questionnaires, together with more traditional sources such as the trade journals and textbooks. The so-called bookkeeping audit of vouching and checking postings and castings, and with the auditor also doing a fair proportion of the clients accounting, was typical down to the 1960s. Major changes then took place, including a decline in accounting work, an increased focus on the balance sheet, and a reliance on sampling and the systems approach. This trend is explained by a growth in the size and professionalism of audit clients. Further change since the 1980s reflects the use of risk assessment, materiality, and analytical review and may be ascribed to the growing commercial pressures on auditors.
Study on reactive power capacity of doubly-fed induction generator

For voltage issue led by large-scale wind farm interconnection into grid. Firstly, power relation of doubly-fed induction generator (DFIG) is analyzed. Further static DFIG model is established. Based on this, a method for analyzing reactive power regulation volume with DFIG operation constraint, static stability and grid code is proposed. By simulation, the result shows that the method is right and can support reactive power regulation of DFIG according to different constraints.
Nitrogen isotope dynamics and fractionation during sedimentary denitrification in Boknis Eck, Baltic Sea

The global marine nitrogen cycle is constrained by nitrogen fixation as a source of reactive nitrogen, and denitrification or anammox on the sink side. These processes with their respective isotope effects set the marine nitrate 15 N-isotope value ( δ 15 N) to a relatively constant average of 5‰. This value can be used to better assess the magnitude of these sources and sink terms, but the underlying assumption is that sedimentary denitrification and anammox, processes responsible for approximately one-third of global nitrogen removal, have little to no isotope effect on nitrate in the water column. We investigated the isotope fractionation in sediment incubations, measuring net denitrification and nitrogen and oxygen stable isotope fractionation in surface sediments from the coastal Baltic Sea (Boknis Eck, northern Germany), a site with seasonal hypoxia and dynamic nitrogen turnover. Sediment denitrification was fast, and regardless of current paradigms assuming little fractionation during sediment denitrification, we measured fractionation factors of 18.9‰ for nitrogen and 15.8‰ for oxygen in nitrate. While the input of nitrate to the water column remains speculative, these results challenge the current view of fractionation during sedimentary denitrification and imply that nitrogen budget calculations may need to consider this variability, as both preferential uptake of light nitrate and release of the remaining heavy fraction can significantly alter water column nitrate isotope values at the sediment–water interface.
Land Use Pattern Adjustment under Ecological Security: Look for Secure Land Use Pattern in China

Since China adopted reform and open policy in 1978, intensive land use pattern changes have been taken place at different scales with the rapid economic growth and fast urbanization, resulting in complex impacts on the regional eco-environmental security. Based on some case studies in Shenzhen, Beijing and the grassland and farming-pastoral zone of North China, the paper used three models-City Expansion Model in Metropolitan Area in Beijing, Basin Rainfall-runoff Model in Shenzhen and Land Use Pattern Adjustment Model in the grassland and farming-pastoral zone of North China to try to demonstrate the possibility to promote ecological security level in China by the rational land use pattern adjustment.
Threshold-Crossing Theory Based Service Requests Analysis Method

The network service providers always prepare hardware design, maintenance and upgrading action plan via experience. This usually leads to large amount of waste resources. Although many complex models have been introduced into the research field of high performance network QOS evaluation, it is hard for such method to be applied into production environment because of the random and complex character of the network service requests and the heavy calculation tasks brought by the models. The Threshold-crossing Theory based Service Requests Analysis Method put forward in this paper is able to determine the necessary concurrent service requests that the server and network hardware have to handle based on the previous service requests data in production environment. This method can be applied into designing, maintaining and upgrading network equipment and provide basis for reducing resource waste, avoiding unnecessary investment and optimizing resources.
The Gains from Basing Grain Storage Decisions on Cash-Future Spreads

TRADITIONALLY, hedging by holding a short position in a futures contract has been viewed as a means of reducing the price risks associated with storage. However, Holbrook Working [5, pp. 436 ff. ] and others have pointed out that firms hedge for other purposes besides simply avoiding risks. Our objective in this study was to identify and measure some of the potential benefits from hedging beyond simple risk reduction. Clearly, the need to predict uncertain future events is a major factor in grain storage decisions. Storing grains is like participating in a game of chance where the odds change each time the game is played. Hedging does not usually change the odds, but the hedger may be able to estimate the odds more accurately than the nonhedger. If so, not only can he avoid risk, but he may actually increase his average earnings over the long run by refusing to play the game, i.e., by refusing to store grains, on those occasions when earning prospects are particularly unfavorable. In most situations, hedging has little effect on average storage earnings when grains are held over the same intervals each year.1 If a manager is to increase his grain storage earnings through hedging, he must be able to predict year-to-year differences in storage earnings on hedged grains and he must respond to these predictions by altering his storage operations from year to year. In this study, least-squares regression was employed to determine whether cash-future spreads could be used effectively to forecast year-to-year differences in corn price movements over the storage season in Michigan. The potential gains from employing such predictions were estimated by incorporating the forecasting equations into decision rules and simulating their application using a Monte Carlo procedure.2
Design and trajectory planning of bipedal walking robot with minimum sufficient actuation system

This paper presents a new type of mechanism and trajectory planning strategy for bipedal walking robot. The newly designed mechanism is able to improve the performance of bipedal walking robot in terms of energy efficiency and weight reduction by utilizing minimum number of actuators. The usage of parallelogram mechanism eliminates the needs of having an extra actuator at the knee joint. This mechanism works together with the joint space trajectory planning in order to realize straight legged walking which cannot be achieved by conventional inverse kinematics trajectory planning due to the singularity. The effectiveness of the proposed strategy is confirmed by computer simulation results. Keywords—Bipedal robot, Energy efficiency, Straight legged walking, Trajectory planning.
Taxing Inelastic Consumption : Income Effects and SNAP Take-Up

We exploit cigarette tax variation across US states from 2001 to 2012 to assess how negative income shocks induce low-income smoking households to enroll in public assistance programs. Using the CEX and a novel CPS household panel on monthly food stamp enrollment, we estimate triple differences models where smoking households are “treated” with higher taxes while nonsmoking households are not. The associated negative income shocks resulting from higher cigarette expenditures increase the probability that low-income smoking households enroll in food stamps. Duration models suggest that higher cigarette taxes significantly shorten the time to take-up for marginal low-income smoking households.
Comparative analysis of two algorithms of combinatorial techniques for testing SPLs — An exploratory study in six SPLs

Software Product Line (SPL) is an approach for developing a family of software systems that has differences among them — SPL variabilities. The number of variability and number of products make the exhaustive tests in SPLs. The generation of valid and representative subset of tests for all possible product configurations is an open challenge. This paper presents a comparative analysis of two algorithms of combinatorial techniques for testing SPLs. Those algorithms were used in six SPLs and the results were evaluated by four metrics. The main contribution of this evaluation was to find the best solution generated by algorithms using metrics which allowing identify the quality of results. Those results confirm that the building of a set of test for SPLs requires thinking about new strategies, because some test methods in SPL consider that features are independent, but their interactions are possible and influence in the product construction and testing.
A Fast and Accurate Eye Tracker Using Stroboscopic Differential Lighting

The use of video-based eye trackers (VETs) for gaze interaction have allowed people with severe motor disabilities to communicate more effectively. Nonetheless, current low cost VETs present limited accuracy and precision that impose several design constraints for gaze-based computer applications. In this paper we present an extension of the differential lighting (DL) technique for pupil detection and tracking using active light sources. The original technique was developed for analog interlaced cameras with external sync signal to synchronize the light sources with the video signal. In this paper we introduce the Stroboscopic DL technique that can be used with any rolling shutter camera, even those with no external sync. We have developed a computer vision technique to adjust the firing of the stroboscopic lights. Our new algorithm also exploits characteristics of pupil images to improve the accuracy of the tracking algorithm. Another advantage of the method is that using flashed pulses of light creates a virtual exposure time, reducing motion blur and temporal shear in the video volume. A real-time 187 fps prototype of the system was implemented using a low cost PS3 camera. Experimental results comparing the performance of our algorithm with Starburst show significant accuracy and speed improvement.
A Model Approach to Off-line English Character Recognition

Recognition rate of handwritten character is still limited due to presence of large variation of shape, scale and format in hand written characters. A sophisticated hand written character recognition system demands a better feature extraction technique that would take care of such variation of hand writing. In this paper, we propose a recognition model based on Hidden Markov Models (HMMs) supported by novel feature extraction technique. Ultimately post-processing is done to enhance the recognition rate further. A data-base of 13000 samples is collected from 100 writers written five times for each character. 2600 samples have been used to train HMM and the rest are used to test recognition model. Using our proposed recognition system we have achieved a good average recognition rate of about 93.24 percent.
Silicon limit electrical characteristics of power devices and Ics

The present paper predicts the silicon limit characteristics of IGBTs, and proposes a novel device structure to achieve the limit. Power MOSFETs have been greatly improved for DC-DC converter applications. It is shown that achieving higher efficiency in the converters necessitates the integration of power MOSFETs and the peripheral circuits in a single package. The authors propose an ideal gate drive to realize the ultimate high speed switching of power MOSFETs. Monolithic Integration of power devices and the gate drive circuit is considered to be an ideal solution. The authors report the development of 12V 10A 1chip DC-DC converters. The authors also propose a new FOM for switching speed comparison of various power devices. Keyword: IGBT, Silicon Limit, MOSFET, MCM, Low impedance gate drive, DC-DC Converter I. EVOLUTION OF POWER DEVICES Power devices have evolved so rapidly that 3.3kV IGBTs have displaced 4.5kV GTOs, which were developed in the late 80’s for traction control of bullet trains. Figure 1 and 2 compare application fields of power devices in 1997 and 2005, respectively[1]. The distinguished difference between the two figures is that most of the applications of GTO and BTr have been replaced by those of IGBT and the module. MOS gate devices are predominantly used in most of the application fields, including LDMOS in power ICs, MOSFETs for low voltage and medium voltage applications and IGBTs for high power applications. Super junction MOSFETs were developed and reported in 1998[2]. They broke through the so-called silicon unipolar device limit in the voltage range from 200V to 900V and significantly enhanced the potential of silicon devices. Another recent remarkable advancements are seen in high speed trench power MOSFETs and power IC technologies. Switching speed of trench MOSFETs has been greatly improved since 1999 in order to meet the requirement of high efficiency and high di/dt of Voltage Regulator Modules for CPUs. The details are described in Section III. Power IC technologies are classified into two categories. One is high voltage SOI power ICs[3,4] for monolithic DC motor control and PDP flat panel display drive. The other is low voltage power ICs for motor control and power supplies[5]. We developed the world first 500V one chip inverter ICs for DC motor control in 1994[4]. In the present paper, We demonstrate 10A operation of 1 chip DC-DC converters in Section IV. Recently, it has been often pointed out that silicon devices face the material limit. It is important to make clear the limit characteristics of silicon devices and the future potential to be exploited. The authors also propose new FOM[6] in order to compare the potential of various power devices. 1M 100K 10K 1K 100 10 100 1K 10K 100K 1M 10M 100M
SERVICE ROBOTIC SYSTEMS FOR GLASS CURTAIN WALLS CLEANING ON THE HIGH-RISE BUILDINGS

The last decade has seen an increasing interest in developing and employing service robots for building maintenance. Cleaning the curtain walls of high-rise buildings is always very dangerous and strenuous. This paper describes three different kinds of cleaning robots developed by the authors cooperated with the researchers in Robotics Institute of BeiHang University. Sky Cleaner 3 for the glass curtain wall of Shanghai Science and Technology Museum, the auto-climbing robot for the spherical surface of the National Grand Theatre of China, and an automatic cleaning gondola for the windows of Beijing Hotel are introduced. The individual robots’ mechanisms and unique characteristics are discussed in detail. The main special features of the three cleaning robots are given as a summary.
Singapore’s policy of non-internationalisation of the Singapore dollar and the Asian dollar market

This paper provides a brief review of Singapore’s experience with its policy of non-internationalisation of the Singapore dollar (SGD policy) and the development of the Asian dollar market in Singapore. However, it needs to be emphasised at the outset that neither of these are capital account restrictions, as the last vestige of exchange controls in Singapore was repealed in 1978. Even prior to their removal in 1978, residents and non-residents alike were free to remit funds into and out of Singapore. This was predicated on Singapore’s outward-oriented economic development strategy.