562 research outputs found
Stress-energy connection: Degravitating the vacuum energy
13th Regional Conference on Mathematical Physics; Antalya; Turkey; 27 October 2010 through 31 October 2010This talk summarizes recent studies on the gravitational properties of vacuum energy in a non-Riemannian geometry formed by the stress-energy tensor of vacuum, matter and radiation. Postulating that the gravitational effects of matter and radiation can be formulated by an appropriate modification of the spacetime connection, we obtain varied geometro-dynamical equations which properly comprise the usual gravitational field equations with, however, Planck-suppressed, non-local, higher-dimensional additional terms. The prime novelty brought about by the formalism is that, the vacuum energy does act not as the cosmological constant but as the source of the gravitational constant. The formalism thus deafens the cosmological constant problem by channeling vacuum energy to gravitational constant. Nevertheless, quantum gravitational effects, if any, restore the problem via the graviton and graviton-matter loops, and the mechanism proposed here falls short of taming such contributions to cosmological constant
Design of Experiment Study of the Parameters that Affect Performance of a Thermoplastic Elastomer Spring of a Hybrid Vehicle Torque Limiter
Due to the C02 emission ratio restrictions, hybrid vehicles become more popular nowadays. Because of that reason, research studies on hybrid vehicles and their powertrain systems have been increased recently. There are several types of hybrid vehicle powertrain structures in use by the car manufacturers; they depend on both the drive modes and the design of conventional and electrical engine layout designed by the car manufacturers. The most known of these structures is the power split hybrid structure. In this study, a thermoplastic elastomer spring was mechanically investigated, which has been designed for torque limiter of a power split type hybrid powertrain. The function of the elastomer spring is to damp the abnormal contact between damper inner metallic components during limiting function. The result of finite element analyses and stiffness measurement result of real parts were compared
The opinions of hotel managers about halal hotel concept: A research in Cappadocia
The number of halal business hotel concept in Turkey in recent years, especially in regions where intensive maritime tourism has been increasing. However, there are no such hotels in the Cappadocia destination. The main purpose of this study is to determine the thoughts of hotel managers in the Cappadocia tourist region on halal tourism and the concept of halal hotels. Using the semi-structured interview technique, open-ended questions were asked by the researchers to the managers of 17 four and
five-star hotels with tourism management certificates in the region. The obtained data were subjected to content analysis and interpreted. The main findings obtained from the research are that hotel managers in Cappadocia see "halal tourism" as a rapidly developing market in the world that will become even more important in the future, and there is no need for a halal hotel concept to promote the demand for the region; they did not intend to make arrangements in accordance with the halal hotel concept and
obtain halal hotel certification in their businesses. They kept prayer rugs in their hotel upon the requests of the guests, they turned their meeting rooms into masjids when requested; and hotel rooms have a sign showing qibla on nightstand drawers
An Analysis of Service Failures and Recovery Strategies in the Turkish Third Party Logistics Service Industry
Service literature indicates that both service failure and service recovery have a strong impact on the business relationships between service providers and their customers. The purpose of this research is twofold: to explore and analyze the most common service failures and implemented recovery strategies in Turkish third party logistics service industry and examine their impact on business relationships. Critical Incident Technique (CIT) was used. Thus, information on critical incidents were collected from both third party logistics service providers (3PLs) and their customers, failures and recovery strategies were categorized and the impact of service failures and recovery strategies on future relationships between customers and 3PLs examined. The findings indicate that service failures are most frequently encountered in customer services and port operations and that symbolic service recovery is the most common recovery strategy implemented by third party logistics service providers. The findings also show that third party logistics service providers and carriers are the most common sources of failure in third party logistics services
Testing Symmergent gravity through the shadow image and weak field photon deflection by a rotating black hole using the M87 and Sgr. A results
In this paper, we study rotating black holes in symmergent gravity, and use
deviations from the Kerr black hole to constrain the parameters of the
symmergent gravity. Symmergent gravity induces the gravitational constant
and quadratic curvature coefficient from the flat spacetime matter
loops. In the limit in which all fields are degenerate in mass, the vacuum
energy can be wholly expressed in terms of and . We
parametrize deviation from this degenerate limit by a parameter
such that the black hole spacetime is dS for and AdS for
. In constraining the symmergent parameters and
, we utilize the EHT observations on the M87* and Sgr. A* black
holes. We investigate first the modifications in the photon sphere and shadow
size, and find significant deviations in the photonsphere radius and the shadow
radius with respect to the Kerr solution. We also find that the geodesics of
time-like particles are more sensitive to symmergent gravity effects than the
null geodesics. Finally, we analyze the weak field limit of the deflection
angle, where we use the Gauss-Bonnet theorem for taking into account the finite
distance of the source and the receiver to the lensing object. Remarkably, the
distance of the receiver (or source) from the lensing object greatly influences
the deflection angle. Moreover, needs be negative for a consistent
solution. In our analysis, the rotating black hole acts as a particle
accelerator and possesses the sensitivity to probe the symmergent gravity.Comment: 22 pages, 9 figures, 2 tables. Accepted for publication in the
European Physical Journal C
(https://link.springer.com/article/10.1140/epjc/s10052-023-11400-6
Thin accretion disk images of the black hole in symmergent gravity
In this paper, we study circular orbits, effective potential, and
thin-accretion disk of a black hole in symmergent gravity within the
Novikov-Thorne model in a way including the energy flux and temperature
distribution. We determine bounds on symmergent gravity parameters and conclude
that the accretion disk could be used as an astrophysical tool to probe
symmergent gravity.Comment: 30 pages. Accepted for publication in Classical and Quantum Gravity,
"Special Issue: Focus on Quantum Gravity Phenomenology in the Multi-Messenger
Era: Challenges and Perspectives"
(https://iopscience.iop.org/article/10.1088/1361-6382/aceb45). arXiv admin
note: text overlap with arXiv:1901.05762, arXiv:2002.00589 by other author
Quasinormal modes and greybody factors of symmergent black hole
Symmergent gravity is an emergent gravity framework in which gravity emerges
guided by gauge invariance, accompanied by new particles, and reconciled with
quantum fields. In this paper, we perform a detailed study of the quasinormal
modes and greybody factors of the black holes in symmergent gravity. Its
relevant parameters are the quadratic curvature term and the vacuum
energy parameter . In our analyses, effects of the both parameters are
investigated. Our findings suggest that, in both positive and negative
direction, large values of the parameter on the quasinormal modes
parallel the Schwarzschild black hole. Moreover, the quasinormal model spectrum
is found to be sensitive to the symmergent parameter . We contrast the
asymptotic iteration and WKB methods in regard to their predictions for the
quasinormal frequencies, and find that they differ (agree) slightly at small
(large) multipole moments. We analyze time-domain profiles of the
perturbations, and determine the greybody factor of the symmergent black hole
in the WKB regime. The symmergent parameter and the quadratic
curvature term are shown to impact the greybody factors
significantly. We provide also rigorous limits on greybody factors for scalar
perturbations, and reaffirm the impact of model parameters.Comment: 23 pages, 16 figures. Published versio
KONYA’DA FAALİYET GÖSTEREN İNŞAAT KOBİLERİNİN DURUMLARI, SEKTÖRDEKİ YERLERİ, SORUNLARI VE ÇÖZÜM ÖNERİLERİ
Ülkemizde ve dünyada küçük ve orta ölçekli işletmeler ekonomik alanda büyük önem taşıyan kuruluşlardır. Özellikle az gelişmiş ve gelişmekte olan ülkelerin sosyal ve ekonomik gelişmelerin her safhasında bu tip işletmeleri görmek mümkündür.Ekonomik hayatın her alanında faaliyet gösteren bu tip işletmeler inşaat sektöründe de bulunmaktadır. Bu çalışmada küçük ve orta ölçekli işletmeler ve bu işletmeler hakkında hazırlanmış çalışma ve araştırmalar gözden geçirilerek Konya ilinde faaliyet gösteren küçük ve orta ölçekli inşaat işletmelerinin yapıları ve işleyişleri incelenmiştir. İncelemede gerekli bilgileri elde edebilmek için 20 adet küçük ve orta ölçekli inşaat işletmesinin kurucu ve yöneticisine, örneği çalışmanın sonunda verilen anket soruları sorularak, cevapları değerlendirilmeye çalışılmıştır. Anketlere verilen cevaplar kodlandırılarak tablo halinde düzenlenmiştir.Sonuç olarak Konya ilinde faaliyet gösteren küçük ve orta ölçekli inşaat işletmelerinin, Konya ilinin sosyal ve ekonomik yapısına etkileri incelenmeye çalışılmıştır
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