5,141 research outputs found
A Paradigm of Reforms with Alternate Energy Sources
This paper focusses on rapidly growing gas demand in the state, its key drivers and solutions. Emphasis is provided on Kuwait’s outlook and ventures into liquefied natural gas (LNG), controls and measures developed for handling constraints in logistical infrastructure. Requirement for tight interaction between the suppliers and consumers was pivotal to segregate different qualities of natural gas to certain consumers. A robust Gas Network system was conceived in the state and it was concluded that under normal operating conditions, it will be possible to supply gas to all essential consumers by combining the available gas from upstream units, refineries and LNG import facility. In this work, a full-blown gas network was simulated to determine transportation capacities, potential restrictions of suppliers and flexibility to use different types of gases available in the system. The study outlined decisive propositions such as the natural gas produced in the state will not be adequate to fulfil the future energy demand, therefore, additional sources such as LNG were more deeply analysed. Moreover, the current energy strategy is primarily based on fossil fuels and hence more efforts were required in implementing renewable energy solutions. In line with this approach, implementation of state sponsored renewable energy projects is underway and by 2030 the share of renewable energy is planned to stretch up to 15% of overall power demand
Studying the Effect of Adding Aleppo Pylon to the Properties of Insulating and Accumulation of Polyvinyl Chloride Films
This research presents a study of the effect of adding natural and modified Aleppo Pylon (Syrian clay) in different proportions to the properties of polymeric films prepared from poly vinyl chlorid (PVC) polymer and dried at three different drying degrees (60oC, 100oC, 150oC). The clay surface was changed from hydrophilic to hydrophobic by treating the surface with quaternary alkyl ammonium salts. Both types of Aleppo Pylone were added to the polymer by weight (0%, 2.5%, 5%, 7.5%, 10%), and the polymeric films were prepared by way of mixing well of PVC polymer and clay. The mixing technique used hexanol as a solvent. The clay was mixed with the polymer at 150 Co temperature using a magnetic stirrer. The effect of adding natural and modified Aleppo Pylon to the properties of water absorption ratio, moisture content, migration of components in moderate, acidic and alkaline aqueous solutions, thermal stability and air permeability of polymeric films prepared from PVC polymer and clay with different drying degrees was studied and compared with them, in order to reach an improved PVC that can be used in the field of packaging
The Effect Of Other Information On Equity Valuation: Kuwait Evidence
Previous studies on the value relevance of accounting information adopt Ohlsons linear information dynamics which, if other information is ignored, leads to a theoretical valuation model solely involving earnings, book value, and net shareholder cash flows or (net dividends). The lack of analysis of other value-relevant data may defeat the effectiveness of the Ohlsons model since the current accounting data cannot fully account for future earnings. The potential implication of ignoring other information is that it could introduce bias into estimated coefficients (e.g. Ohlson, 1995; Hand and Landsman, 2005). This study examines the effect of introducing other information proxied by lagged valuation error on equity valuation, utilizing a sample of non-financial companies listed at the Kuwait Stock Exchange (KSE) over the period 2003 to 2009. Empirical results of this study reveal that our proxy for other information appears to capture valuation implications of information other than current variables in the linear information dynamic setting. Results also reveal that adding other information to the valuation model clearly reduces the coefficients on earnings and dividends, and increases the coefficient of book value; however, book value and earnings remain significantly associated with stock prices. As a consequence, current accounting variables appear to be capturing some, but not all, of other information when this variable is omitted. We conclude that other information is an important factor in determining the market value of firms and hence should not be omitted in studies examining the value relevance of accounting information
Predicting Intermediate Storage Performance for Workflow Applications
Configuring a storage system to better serve an application is a challenging
task complicated by a multidimensional, discrete configuration space and the
high cost of space exploration (e.g., by running the application with different
storage configurations). To enable selecting the best configuration in a
reasonable time, we design an end-to-end performance prediction mechanism that
estimates the turn-around time of an application using storage system under a
given configuration. This approach focuses on a generic object-based storage
system design, supports exploring the impact of optimizations targeting
workflow applications (e.g., various data placement schemes) in addition to
other, more traditional, configuration knobs (e.g., stripe size or replication
level), and models the system operation at data-chunk and control message
level.
This paper presents our experience to date with designing and using this
prediction mechanism. We evaluate this mechanism using micro- as well as
synthetic benchmarks mimicking real workflow applications, and a real
application.. A preliminary evaluation shows that we are on a good track to
meet our objectives: it can scale to model a workflow application run on an
entire cluster while offering an over 200x speedup factor (normalized by
resource) compared to running the actual application, and can achieve, in the
limited number of scenarios we study, a prediction accuracy that enables
identifying the best storage system configuration
Factors affecting the adoption and use of urban air mobility
Technological advances have recently led to the development of urban air mobility (UAM), an alternative transportation mode with several concepts including vehicles operated by on-demand fully-automated vertical take-off and landing aircraft (VTOL) for intra-city passenger transportation. However, despite a growing interest in UAM, understanding users’ perceptions to it remains limited. This research aims to identify and quantify the factors affecting the adoption and use of UAM, based on relevant tools from the literature, such as recurring factors in studies on aerial vehicle concepts, ground autonomous vehicles, but also acceptance models, such as the Technology Acceptance Model by Davis et al. (1989). A stated-preference survey was developed to assess the perception of users in terms of adoption time horizon, including options such as the first six years of the service’s implementation, “unsure”, and “never”. The obtained results were evaluated using exploratory factor analyses, and the specification and estimation of suitable discrete choice models, multinomial logit models (MNLs) and ordered logit models (OLMs), with adoption time horizon as dependent variable. Findings revealed the importance of safety and trust, affinity to automation, data concerns, social attitude, and socio-demographics for adoption. Factors, such as the value of time savings, the perception of automation costs, and service reliability, were also found to be highly influential. There was also an indication that skeptical respondents, i.e. answering “unsure”, had a behavior similar to late and non-adopters, i.e. adoption time horizon higher than six years or answering “never”. The summarized results were represented in an extended Technology Acceptance Model for urban air mobility, and provided insights for policymakers and industrial stakeholders
A New Sensorless Hybrid MPPT Algorithm Based on Fractional Short-Circuit Current Measurement and P&O MPPT
This paper presents a new maximum power point tracking (MPPT) method for photovoltaic (PV) systems. The proposed method improves the working of the conventional perturb and observe (P&O) method in changing environmental conditions by using the fractional short-circuit current (FSCC) method. It takes the initial operating point of a PV system by using the short-circuit current method and later shifts to the conventional P&O technique. The advantage of having this two-stage algorithm is rapid tracking under changing environmental conditions. In addition, this scheme offers low-power oscillations around MPP and, therefore, more power harvesting compared with the common P&O method. The proposed MPPT decides intelligently about the moment of measuring short-circuit current and is, therefore, an irradiance sensorless scheme. The proposed method is validated with computer software simulation followed by a dSPACE DS1104-based experimental setup. A buck-boost dc-dc converter is used for simulation and experimental confirmation. Furthermore, the reliability of the proposed method is also calculated. The results show that the proposed MPPT technique works satisfactorily under given environmental scenarios
Investigating the Magnetic Structure of Interplanetary Coronal Mass Ejections using Simultaneous Multi-Spacecraft In situ Measurements
In situ measurements from spacecraft typically provide a time series at a
single location through coronal mass ejections (CMEs) and they have been one of
the main methods to investigate CMEs. CME properties derived from these in situ
measurements are affected by temporal changes that occur as the CME passes over
the spacecraft, such as radial expansion and ageing, as well as spatial
variations within a CME. This study uses multi-spacecraft measurements of the
same CME at close separations to investigate both the spatial variability (how
different a CME profile is when probed by two spacecraft close to each other)
and the so-called ageing effect (the effect of the time evolution on in situ
properties). We compile a database of 19 events from the past four decades
measured by two spacecraft with a radial separation <0.2 au and an angular
separation <10{\deg}. We find that the average magnetic field strength measured
by the two spacecraft differs by 18% of the typical average value, which
highlights non-negligible spatial or temporal variations. For one particular
event, measurements taken by the two spacecraft allow us to quantify and
significantly reduce the ageing effect to estimate the asymmetry of the
magnetic field strength profile. This study reveals that single-spacecraft time
series near 1 au can be strongly affected by ageing and that correcting for
self-similar expansion does not capture the whole ageing effect.Comment: Accepted for publication at ApJ. 18 pages, 6 figures, 2 table
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