4,807 research outputs found
Anomalous resonant production of the fourth family up type quarks at the LHC
Considering the present limits on the masses of fourth family quarks from the
Tevatron experiments, the fourth family quarks are expected to have mass larger
than the top quark. Due to their expected large mass they could have different
dynamics than the quarks of three families of the Standard Model. The resonant
production of the fourth family up type quark t' has been studied via anomalous
production subprocess gq_i-->t' (where q_i=u,c) at the LHC with the center of
mass energy 10 TeV and 14 TeV. The signatures of such process are discussed
within the SM decay modes. The sensitivity to anomalous coupling
\kappa/\Lambda=0.1 TeV^(-1) can be reached at \sqrt{s}=10 TeV and L_int=100
pb^(-1).Comment: 14 pages, 13 figures, 7 table
Impacts of battery characteristics, driver preferences and road network features on travel costs of a plug-in hybrid electric vehicle (PHEV) for long-distance trips
Cataloged from PDF version of article.In a road network with refueling and fast charging stations, the minimum-cost driving path of a plug-in hybrid electric vehicle (PHEV) depends on factors such as location and availability of refueling/fast charging stations, capacity and cost of PHEV batteries, and driver tolerance towards extra mileage or additional stopping. In this paper, our focus is long-distance trips of PHEVs. We analyze the impacts of battery characteristics, often-overlooked driver preferences and road network features on PHEV travel costs for long-distance trips and compare the results with hybrid electric and conventional vehicles. We investigate the significance of these factors and derive critical managerial insights for shaping the future investment decisions about PHEVs and their infrastructure. In particular, our findings suggest that with a certain level of deployment of fast charging stations, well established cost and emission benefits of PHEVs for the short range trips can be extended to long distance. Drivers׳ stopping intolerance may hamper these benefits; however, increasing battery capacity may help overcome the adverse effects of this intolerance
Regenerator Location Problem and survivable extensions: A hub covering location perspective
Cataloged from PDF version of article.In a telecommunications network the reach of an optical signal is the maximum distance it can traverse before its quality degrades. Regenerators are devices to extend the optical reach. The regenerator placement problem seeks to place the minimum number of regenerators in an optical network so as to facilitate the communication of a signal between any node pair. In this study, the Regenerator Location Problem is revisited from the hub location perspective directing our focus to applications arising in transportation settings. Two new dimensions involving the challenges of survivability are introduced to the problem. Under partial survivability, our designs hedge against failures in the regeneration equipment only, whereas under full survivability failures on any of the network nodes are accounted for by the utilization of extra regeneration equipment. All three variations of the problem are studied in a unifying framework involving the introduction of individual flow-based compact formulations as well as cut formulations and the implementation of branch and cut algorithms based on the cut formulations. Extensive computational experiments are conducted in order to evaluate the performance of the proposed solution methodologies and to gain insights from realistic instances. (C) 2014 Elsevier Ltd. All rights reserved
Minimum cost path problem for Plug-in Hybrid Electric Vehicles
Cataloged from PDF version of article.We introduce a practically important and theoretically challenging problem: finding
the minimum cost path for plug-in hybrid electric vehicles (PHEVs) in a network
with refueling and battery switching stations, considering electricity and
gasoline as sources of energy with different cost structures and limitations. We
show that this problem is NP-complete even though its electric vehicle and conventional
vehicle special cases are polynomially solvable. We propose three solution
techniques: (1) a mixed integer quadratically constrained program that incorporates
non-fuel costs such as vehicle depreciation, battery degradation and stopping,
(2) a dynamic programming based heuristic and (3) a shortest path heuristic. We
conduct extensive computational experiments using both real world road network
data and artificially generated road networks of various sizes and provide signifi-
cant insights about the effects of driver preferences and the availability of battery
switching stations on the PHEV economics. In particular, our findings show that
increasing the number of battery switching stations may not be enough to overcome
the range anxiety of the drivers
Can Yardstick Competition Reduce Waiting Times?
Yardstick competition is a regulatory scheme for local monopolists (e.g., hospitals), where the monopolist's reimbursement is linked to performance relative to other equivalent monopolists. This regulatory scheme is known to provide cost-reduction incentives and serves as the theoretical underpinning behind the hospital prospective reimbursement system used throughout the developed world. This paper uses a game-theoretic queueing model to investigate how yardstick competition performs in service systems (e.g., hospital emergency departments), where in addition to incentivizing cost reduction the regulator wants to incentivize waiting time reduction. We first show that the form of cost-based yardstick competition used in practice results in inefficiently long waiting times. We then demonstrate how yardstick competition can be appropriately modified to achieve the dual goal of cost and waiting-time reduction. In particular, we show that full efficiency (first-best) can be restored if the regulator makes the providers' reimbursement contingent on their service rates and is also able to charge a provider-specific "toll" to consumers. More importantly, if such a toll is not feasible, as may be the case in healthcare, we show that there exists an alternative and particularly simple yardstick-competition scheme, which depends on the average waiting time only, that can significantly improve system efficiency (second-best). This scheme is easier to implement as it does not require the regulator to have detailed knowledge of the queueing discipline. We conclude with a numerical investigation that provides insights on the practical implementation of yardstick competition for hospital Emergency Departments and also present a series of modelling extensions
An analysis of cyclic scheduling problems in robot centered cells
Cataloged from PDF version of article.The focus of this study is a robot centered cell consisting of m computer numerical control (CNC)
machines producing identical parts. Two pure cycles are singled out and further investigated as
prominent cycles in minimizing the cycle time. It has been shown that these two cycles jointly
dominate the rest of the pure cycles for a wide range of processing time values. For the remaining
region, the worst case performances of these pure cycles are established. The special case of 3-machines
is studied extensively in order to provide further insight for the more general case. The situation where
the processing times are controllable is analyzed. The proposed pure cycles also dominate the rest when
the cycle time and total manufacturing cost objectives are considered simultaneously from a bicriteria
optimization point of view. Moreover, they also dominate all of the pure cycles in in-line robotic cells.
Finally, the efficient frontier of the 3-machine case with controllable processing times is depicted as an
example
State-of-the-Art System Solutions for Unmanned Underwater Vehicles
Unmanned Underwater Vehicles (UUVs) have gained popularity for the last decades, especially for the purpose of not risking human life in dangerous operations. On the other hand, underwater environment introduces numerous challenges in navigation, control and communication of such vehicles. Certainly, this fact makes the development of these vehicles more interesting and engineering-wise more attractive. In this paper, we first revisit the existing technology and methodology for the solution of aforementioned problems, then we try to come up with a system solution of a generic unmanned underwater vehicles
Electrode Fixation with Bone Cement or Stimloc (R) in Deep Brain Stimulation Surgery: A Comparative Study
AIM: To examine the postoperative outcomes of electrode fixation using bone cement and Stimloc?? in patients with Parkinson???s MATERIAL and METHODS: Between 2016 and 2018, permanent electrode fixation was performed in 30 patients with PD, of which 15 received bone cement and the remaining 15 received Stimloc??. Data regarding preoperative Unified Parkinson???s Disease Rating Scale (UPDRS) III scores, levodopa equivalent daily dose (LEDD) values, surgery duration, and the fixation technique used were recorded. Brain computed tomography was performed for early postoperative evaluation of pneumocephalus and possible hematoma as well as for the determination of migration 1 year postoperatively. UPDRS III scores and LEDD values were re-evaluated 1 year postoperatively; surgery duration, clinical effectiveness, and complication rates were compared between the two fixation techniques. RESULTS: A statistically significant difference in application time was observed between the two techniques (bone cement: 21 min, Stimloc??: 6 min). After 1 year from surgery, 0.92- and 0.88-mm migrations were observed in the bone cement and Stimloc?? groups, respectively. A significant correlation between migration and the pneumocephalus volume was observed in both groups. No differences were observed between the groups regarding infection, migration, pneumocephalus volume, wound erosion, and CONCLUSION: Stimloc?? is preferred over bone cement for electrode fixation in DBS surgeries as it is associated with shorter application duration; this increases patient comfort and tolerance during awake surgery. Clinical efficacy and complication rates associated with both techniques are similar
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