869 research outputs found
Profitability of the On-Balance Volume Indicator
In the literature, there is a lack of empirical studies documenting the profitability of volume-based technical indicators. This paper evaluates the profitability of the On-Balance Volume (OBV) trading rule. Our result shows that the OBV trading rule is increasingly profitable and rewards investors with notable returns in the stock markets of Greater China.On-Balance Volume, Moving Average, Market Efficiency.
Space Station communications and tracking systems modeling and RF link simulation
In this final report, the effort spent on Space Station Communications and Tracking System Modeling and RF Link Simulation is described in detail. The effort is mainly divided into three parts: frequency division multiple access (FDMA) system simulation modeling and software implementation; a study on design and evaluation of a functional computerized RF link simulation/analysis system for Space Station; and a study on design and evaluation of simulation system architecture. This report documents the results of these studies. In addition, a separate User's Manual on Space Communications Simulation System (SCSS) (Version 1) documents the software developed for the Space Station FDMA communications system simulation. The final report, SCSS user's manual, and the software located in the NASA JSC system analysis division's VAX 750 computer together serve as the deliverables from LinCom for this project effort
THE EFFECTS OF USER PARTICIPATION ON SYSTEM SUCCESS: TOWARD A CONTINGENCY THEORY OF USER SATESFACTION
User participation is an important construct in IS research. It is also a frequently employed practical implementation strategy. However, research findings concerning the effects of user participation on system success are mixed and inconclusive. This study reviews a contingency theory of attitude change, proposes competing models, and empirically tests the models in end-user computing involving multiple end-user groups. Results lend support to the Cognition Fit Model. Other models receive only partial support
Effect of Tai Chi Training on Dual-Tasking Performance That Involves Stepping Down among Stroke Survivors: A Pilot Study
Descending stairs demands attention and neuromuscular control, especially with dual-tasking. Studies have demonstrated that stroke often degrades a survivor’s ability to descend stairs. Tai Chi has been shown to improve dual-tasking performance of healthy older adults, but no such study has been conducted in stroke survivors. This study investigated the effect of Tai Chi training on dual-tasking performance that involved stepping down and compared it with that of conventional exercise among stroke survivors. Subjects were randomized into Tai Chi (n=9), conventional exercise (n=8), and control (n=9) groups. Those in the former two groups received 12-week training. Assessments included auditory Stroop test, stepping down test, and dual-tasking test involving both simultaneously. They were evaluated before training (time-1), after training (time-2), and one month after training (time-3). Tai Chi group showed significant improvement in the auditory Stroop test from time-1 to time-3 and the performance was significantly better than that of the conventional exercise group in time-3. No significant effect was found in the stepping down task or dual-tasking in the control group. These results suggest a beneficial effect of Tai Chi training on cognition among stroke survivors without compromising physical task performance in dual-tasking. The effect was better than the conventional exercise group. Nevertheless, further research with a larger sample is warranted
Investigation into the numerical model behaviour of Belleville washers in cold roll forming
With the steadily increase in demand for roll formed products due to their application for fields such as automotive, construction, architecture, etc., roll forming companies are challenge with rising customer demands. Companies are struggling to bring a product through from design to manufacture at improved rates, whilst achieving tighter tolerances. The roll forming process may also induce undesirable forming defects such as twist, distortion and straightness problems.Traditionally these issues would be resolved through an empirical approach which heavily relies on the designer's expertise and intuition. This approach can increase undesired development costs due to materials wasted and time delayed. Over the years, numerical simulations have been deployed to try and geometrically validate these defects and ultimately reduce the development phase of a product. The designer has the capability to virtually investigate changes in specific parameters without the risk of expensive tooling costs. The industry partner of this project, Hadley Group, Birmingham, implement Belleville washers into the roll tool configuration. The purpose of these washers is to apply pressure to the strip during roll forming in order to drive material through each forming station. They are also used to adjust the gap between the top and bottom forming rolls, since the incoming material gauge can vary by the nominal tolerance values from coil to coil. For the purpose of this paper, an investigation is carried out focusing on an individual parameter within the finite element analysis (FEA) of the cold roll forming process, i.e. the 'unknown' spring acting on the top roll during the forming process due to the implementation of Belleville washers in the pillar set up. The work explained in this paper shows the eects of the pressure applied to the forming process on the geometric attributes of the section being formed. The outcome will determine the viability of this parameter, which may ultimately require the numerical design methodology of roll formed products to be amended accordingly
Resonant Shattering Flares as Multimessenger Probes of the Nuclear Symmetry Energy
The behaviour of the nuclear symmetry energy near saturation density is
important for our understanding of dense nuclear matter. This density
dependence can be parameterised by the nuclear symmetry energy and its
derivatives evaluated at nuclear saturation density. In this work we show that
the core-crust interface mode of a neutron star is sensitive to these
parameters, through the (density-weighted) shear-speed within the crust, which
is in turn dependent on the symmetry energy profile of dense matter. We
calculate the frequency at which the neutron star quadrupole ()
crust-core interface mode must be driven by the tidal field of its binary
partner to trigger a Resonant Shattering Flare (RSF). We demonstrate that
coincident multimessenger timing of an RSF and gravitational wave chirp from a
neutron star merger would enable us to place constraints on the symmetry energy
parameters that are competitive with those from current nuclear experiments.Comment: 15 pages, 19 figures, accepted in MNRA
The reproductive cycle of the thorny skate (Amblyraid radiata) in the western Gulf of Maine
The thorny skate (Amblyraja radiata) is a large species of skate that is endemic to the waters of the western north Atlantic in the Gulf of Maine. Because the biomass of thorny skates has recently declined below threshold levels mandated by the Sustainable Fisheries Act, commercial harvests from this region are prohibited. We have undertaken a comprehensive study to gain insight into the life history of this skate. The present study describes and characterizes the reproductive cycle of female and male thorny skates, based on monthly samples taken off the coast of New Hampshire, from May 2001 to May 2003. Gonadosomatic index (GSI), shell gland weight, follicle size, and egg case formation, were assessed for 48 female skates. In general, these reproductive parameters remained relatively constant throughout most of the year. However, transient but significant increases in shell gland weight and GSI were observed during certain months. Within the cohort of specimens sampled monthly throughout the year, a subset of females always had large preovulatory follicles present in their ovaries. With the exception of June and September specimens, egg cases undergoing various stages of development were observed in the uteri of specimens captured during all other months of the year. For males (n=48), histological stages Ill through VI (SIII-SVI) of spermatogenesis, GSI, and hepatosomatic index (HSI) were examined. Although there appeared to be monthly fluctuations in spermatogenesis, GSI, and HSI, no significant differences were found. The production and maintenance of mature spermatocysts (SVI) within the testes was observed throughout the year. These findings collectively indicate that the thorny skate is reproductively active year round
Constraining Nuclear Symmetry Energy with Multi-messenger Resonant Shattering Flares
Much effort is devoted to measuring the nuclear symmetry energy through
neutron star (NS) and nuclear observables. Since matter in the NS core may be
non-hadronic, observables like radii and tidal deformability may not provide
reliable constraints on properties of nucleonic matter. We demonstrate that
coincident timing of a resonant shattering flare (RSF) and gravitational wave
signal during binary NS inspiral probes the crust-core transition region and
provides constraints on the symmetry energy comparable to terrestrial nuclear
experiments. We show that nuclear masses, RSFs and measurements of NS radii and
tidal deformabilities constrain different density ranges of the EOS, providing
complementary probes.Comment: 7 pages, 3 figures submitted to PR
Validation of a finite element model of the cold roll forming process on the basis of 3D geometric accuracy
Cold roll forming is an incremental sheet metal forming process used to supply products to numerous industries such as automotive, architecture and construction, etc. In recent years there has been an increase in the demand by customers for high value products, through the forming of high strength materials, or complex profiles. Such demands increase the challenges faced by the tooling designer to bring a successful product through from design to manufacture, on time and within specification. Finite element (FE) simulations are increasingly applied in industry due to the desired advantage of reducing design iterations by allowing the designer to investigate the effects of parameter changes, without the risk of expensive tooling costs. Some successful validation of the numerical modelling of the cold roll forming process can be found in literature, in particular when analysing the strain distribution across the material or comparing the final rolled profile geometry. However, cold roll forming is a continuous process and no one has published work on the measurement of the profile on a pass to pass basis, in particular, the three dimensional geometry of the profile. Experimental trials were carried out to obtain a 3D point cloud model of the top surface of a roll formed section. This investigation aimed to quantify how accurate FE simulation may be in relation to physical data
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