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801.
It is widely recognized that individual decision-making is subject to the evaluation of gains and losses around a reference
point. The estimation of discrete choice models increasingly use data from stated choice experiments which are pivoted around
a reference alternative. However, to date, the specification of a reference alternative in transport studies has been fixed,
whereas it is common to observe individuals adjusting their preferences according to a change in their reference point. This
paper focuses on individual reactions, in a freight choice context, to a negative change in the reference alternative values,
identifying the behavioural implications in terms of loss aversion and diminishing sensitivity. The results show a significant
adjustment in the valuation of gains and losses around a shifted reference alternative. In particular, we find an average
increase in loss aversion for cost and time attributes, and a substantial decrease for punctuality. These findings are translated
to significant differences in the willingness to pay and willingness to accept measures, providing supporting evidence of
respondents’ behavioural reaction. 相似文献
802.
Reiner Onken Horst Garbe Stefan Schröder Michael Janik 《Journal of Marine Science and Technology》2010,15(4):427-433
A novel self-contained probe is presented which measures the sediment temperature of tidal flats between the surface and 40-cm
depth, and indicates whether the flats are flooded or dry. Depending on the selected acquisition interval, the endurance of
the probe is more than 6 months. It can be applied for the investigation of thermodynamic properties of the tidal flats impacting
physical and biological processes. Intensive tests have shown that the probe is robust and reliable and can be easily operated
by a single person. In case of rough weather conditions, the usage of scour protectors is recommended. 相似文献
803.
Seven adjustments of convergent-type Vortex Tube (VT) with different throttle angles were applied. The adjustments were made to analyze the influences of such angles on cold and hot temperature drops as well as flow structures inside the VTs. An experimental setup was designed, and tests were performed on different convergent VT configurations at injection pressures ranging from 0.45 to 0.65 MPa. The angles of the throttle valve were arranged between 30° to 90°, and the numbers of injection nozzles ranged between 2 and 6. Laboratory results indicated that the maximum hot and cold temperature drops ranged from 23.24 to 35 K and from 22.87 to 32.88 K, respectively, at four injection nozzles. Results also showed that temperature drop is a function of hot throttle valve angle with the maximum hot and cold temperature drops depending on the angle applied. We used graphs to demonstrate the changes in the cold and hot temperature drops with respect to hot throttle angle values. These values were interpreted and evaluated to determine the optimum angle, which was 60°. The CFD outputs agreed very well with the laboratory results. The proposed CFD results can help future researchers gain good insights into the complicated separation process taking place inside the VTs. 相似文献
804.
Small sample size problem is one of the main problems that heavy numerical control (NC) machine tools encounter in their reliability assessment. In order to deal with the small sample size problem, many indirect reliability data such as reliability data of similar products, expert opinion, and engineers’ experience are used in reliability assessment. However, the existing mathematical theories cannot simultaneously process the above reliability data of multiple types, and thus imprecise probability theory is introduced. Imprecise probability theory can simultaneously process multiple reliability data by quantifying multiple uncertainties (stochastic uncertainty, fuzzy uncertainty, epistemic uncertainty, etc.) together. Although imprecise probability theory has so many advantages, the existing natural extension models are complex and the computation result is imprecise. Therefore, they need some improvement for the better application of reliability engineering. This paper proposes an improved imprecise reliability assessment method by introducing empirical probability distributions to natural extension model, and the improved natural extension model is applied to the reliability assessment of heavy NC machine tool spindle to illustrate its effectiveness. 相似文献
805.
This article presents a method named pseudo-inverse to solve the optimal thrust allocation of dynamic positioning (DP) system,
proposes to optimally determine the azimuth angle of thrusters instead of man-control or semi-auto control, and combines with
the pseudo-inverse methods to get the optimal solutions for dynamic positioning control system. It is able to greatly reduce
the risk of manual mode. Three different kinds of modes are proposed and detailedly illuminated, and can be used to solve
much more complex nonlinear constraint problems, such as typical forbidden vector boundary. Several illustrative examples
are provided to demonstrate the effectiveness and correctness of the proposed thrust allocation modes. 相似文献
806.
Singfat Chu 《Transportation》2011,38(2):215-226
The Vehicle Quota System manages vehicle ownership in Singapore by making the procurement of a Certificate of Entitlement
(COE) a prerequisite for the registration of a new vehicle. The procurement is done during uniform price auctions of quotas
of COEs currently held on a twice-a-month schedule. The auction format which started out as sealed bids in May 1990 changed
to open bids in July 2001. This paper uses a regression model framework to investigate if this shift in auction format has
resulted in lower COE premium volatility and a better reflection of demand and supply forces. The empirical results are pertinent
to transport policy analysis. A suggestion in the form of incentives for early bids is also made to improve the efficiency
of the open bids auction. 相似文献
807.
Omer Kemal Kinaci 《船舶与海洋工程学报》2016,15(2):136-143
Aircraft flying close to the ground benefit from enhanced efficiency owing to decreased induced drag and increased lift. In this study, a mathematical model is developed to simulate the takeoff of a wing near the ground using an Iterative Boundary Element Method (IBEM) and the finite difference scheme. Two stand-alone sub-codes and a mother code, which enables communication between the sub-codes, are developed to solve for the self-excitation of the Wing-In-Ground (WIG) effect. The aerodynamic force exerted on the wing is calculated by the first sub-code using the IBEM, and the vertical displacement of the wing is calculated by the second sub-code using the finite difference scheme. The mother code commands the two sub-codes and can solve for the aerodynamics of the wing and operating height within seconds. The developed code system is used to solve for the force, velocity, and displacement of an NACA6409 wing at a 4° Angle of Attack (AoA) which has various numerical and experimental studies in the literature. The effects of thickness and AoA are then investigated and conclusions were drawn with respect to generated results. The proposed model provides a practical method for understanding the flight dynamics and it is specifically beneficial at the pre-design stages of a WIG effect craft. 相似文献
808.
The properties and electronic structure of Fe under pressures of 0–30GPa have been studied by first principles employing the
density functional theory (DFT), the ultra-soft pseudo-potentials (USPP) and the generalized gradient approximation (GGA).
The calculating results show that there is a structural transition from magnetic body-centered cubic (bcc) to nonmagnetic
hexagonal-close-packed (hcp) structure for Fe around 11GPa pressure. There is a pseudogap both in the density of states (DOS)
for bcc and hcp Fe. The pseudogap of bcc Fe is deeper and wider than that of hcp Fe. The elastic modulus is obtained by Voigt-Reuss-Hill
averaging scheme. The results indicate that the elastic properties of bcc Fe enhance with pressure except for elastic stiffness
constant C
11, shear modulus G and elastic modulus E at the transition pressure, while the elastic properties of hcp Fe increase linearly with pressure. Magnetic bcc Fe is ductile,
and hcp Fe becomes ductile from brittle around 25GPa. 相似文献
809.
Peter Muirhead 《WMU Journal of Maritime Affairs》2011,10(2):241-242
810.
杨明豪 《上海交通大学学报(英文版)》2011,16(5):586-592
This paper aims at analyzing the security issues that lie in the application layer (AL) protocols when users connect to the
Internet via a wireless local area network (WLAN) through an access point. When adversaries launch deauthentication flood
attacks cutting users’ connection, the connection managers will automatically research the last access point’s extended service
set identifier (ESSID) and then re-establish connection. However, such re-connection can lead the users to a fake access point
with the same ESSID set by attackers. As the attackers hide behind users’ access points, they can pass AL’s authentication
and security schemes, e.g. secure socket layer (SSL). We have proved that they can even spy on users’ account details, passwords,
data and privacy. 相似文献