Hole Heat Research Articles

Thermodynamics of charged accelerating AdS black holes and holographic heat engines

Using a reasonable choice in normalizing the timelike Killing vector, we investigate the thermodynamic properties of charged accelerating Anti-de Sitter (AdS) black holes. We find that the expression of the thermodynamic mass in the first law of thermodynamics displays an inextricably intertwining behavior with the charge due to the unusual asymptotic structure of the accelerating black holes. Meanwhile, the thermodynamic length as a potential conjugate to the varying cosmic string tension is introduced and analyzed in detail, and the possible phase behavior of the charged accelerating black holes is also discussed in a standard thermodynamic analysis. Furthermore, we also investigate the properties of holographic heat engines with charged accelerating AdS black holes as the working substance in a benchmarking scheme. We find that the efficiencies of the black hole heat engines can be influenced by both the size of the benchmark circular cycle and the cosmic string tension. More interestingly, the existence of charge may significantly increase the efficiencies of the black hole heat engines and make them be more sensitive to a varying cosmic string tension. A cross-comparison of the efficiencies of different black hole heat engines suggests that the acceleration also increases the efficiency and renders it more sensitive as the charge varies.

Thermodynamics of novel dilatonic BTZ black holes coupled to Born-Infeld electrodynamics

In this work, thermodynamic properties of the three-dimensional charged dilatonic black holes are considered in the presence of Born-Infeld nonlinear electrodynamics. The exact nonlinearly charged black hole solutions to the coupled Einstein-Born-Infeld three-dimensional field equations in the presence of a dilatonic scalar field are constructed. Some new classes of nonlinearly charged dilatonic black hole solutions are distinguished according to different values of the parameters in the theory. The thermodynamics of all of the new Einstein-Born-Infeld-dilaton black holes are studied separately. We show that the thermodynamic quantities satisfy the first law of black hole thermodynamics. Through the canonical ensemble method and noting the black hole heat capacity, we analyze the stability and thermodynamic phase transitions of all of the new Einstein-Born-Infeld-dilaton black holes.

Thermodynamics and its quantum correction of non-commutative Schwarichild black hole

Black hole thermodynamics establishes a deep and satisfying link to gravity, thermodynamics, and quantum theory. And, the thermodynamic property of black hole is essentially a quantum feature of gravity. In this paper, in order to study the influence of the quantum gravity effect on the quantum properties of black hole, we study the thermodynamics and its quantum correction to a non-commutative black hole. First of all, the temperature of the non-commutative Schwarichild black hole is calculated by using three different methods: surface gravity, tunneling effects and the first law of black hole thermodynamics. It is found that the same hole temperature is obtained by means of the surface gravity and tunneling effects. However, by using the first law of black hole thermodynamics, different results are derived from the first two methods. Therefore, we incline to the result obtained by surface gravity and tunneling effects, and the temperature obtained by the thermodynamic law needs modifying. That is, for the non-commutative black hole, there is a contradiction to the first law of thermodynamics. To calculate the temperature and other thermodynamic quantities for the non-commutative Schwarichild black hole, we use the corrected first law of black hole thermodynamics proposed in the literature. It is found that the black hole temperature derived by the corrected first law is the same as the temperature obtained by the surface gravity and the tunneling model, and the black hole entropy still follows Beckenstein-Hawking area law. Also, the heat capacity of the black hole is obtained and analyzed. It is seen that when the horizon radius and non-commutative parameter satisfy the particular conditions, the heat capacity is positive and the non-commutative black holes are thermodynamically stable. This is a different result from that of the usual Schwarichild black hole. Further, by studying the influence of generalized uncertainty principle on non-commutative black hole thermodynamics, the quantum corrections from generalized uncertainty principle for temperature, entropy and heat capacity of the non-commutative Schwarzschild black hole are given. It is found that with considering this quantum gravity effect, the obtained black hole entropy contains the item of are alogarithm. If the effect of the generalized uncertainty principle is neglected, the corrected black hole entropy can return to that in the usual case of Beckenstein-Hawing area law. Similarly, the corrected black hole temperature and heat capacity can also return to their counterparts in the case of usual Schwarzschild black hole when this quantum gravity effect is ignored.

Benchmarking black hole heat engines, II

We extend to nonstatic black holes our benchmarking scheme that allows for cross–comparison of the efficiencies of asymptotically AdS black holes used as working substances in heat engines. We use a circular cycle in the [Formula: see text] plane as the benchmark cycle. We study Kerr black holes in four spacetime dimensions as an example. As in the static case, we find an exact formula for the benchmark efficiency in an ideal gas-like limit, which may serve as an upper bound for rotating black hole heat engines in a thermodynamic ensemble with fixed angular velocity. We use the benchmarking scheme to compare Kerr to static black holes charged under Maxwell and Born–Infeld sectors.

Comparison of percussion laser drilling quality with and without water-based ultrasonic assistance

A millisecond-pulsed percussion laser drilling technique using water-based ultrasonic assistance is reported for drilling nickel super-alloy GH4037 sheets with 12-mm-thickness. Influence of ultrasonic vibration on drilling quality including hole taper angle, hole sidewall quality, recast layer microstructure, and hardness distribution of hole heat affected zone (HAZ) is analyzed through comparing holes drilled without ultrasonic assistance. Recast layer reduction, grain refinement, and HAZ hardness increase induced by ultrasonic assistance are also analyzed. It is shown that ultrasonic vibration improves percussion laser drilling quality by reducing hole taper angle, cleaning hole sidewall, decreasing hole defects, reducing recast layer thickness, refining grains, decreasing hole sidewall surface roughness, and increasing micro hardness.

Thermodynamics of novel charged dilaton black holes in gravity's rainbow

In the present work, we have studied the thermodynamical properties of black holes arising as the solutions of the four-dimensional dilaton gravity coupled to Maxwell's electrodynamics in gravity's rainbow. This theory allows three classes of asymptotically non-flat and non-AdS black hole solutions. We showed that the self-interacting scalar function, as the solution to the scalar field equation, can be written as the linear combination of three Liouville-type potentials. The thermodynamical quantities are identified and in particular, a generalized Smarr formula is derived. It is shown that, although the thermodynamic quantities are affected by the rainbow functions, the validity of the black hole thermodynamical first law is supported. The thermodynamic stability of the solutions have been analyzed through the black hole heat capacity. We have shown that, even in the presence of the rainbow functions, the black holes can be locally stable in the sense that there exists a range of the horizon radiuses for which the heat capacity is positive.

Accelerating AdS black holes as the holographic heat engines in a benchmarking scheme

We investigate the properties of holographic heat engines with an uncharged accelerating non-rotating AdS black hole as the working substance in a benchmarking scheme. We find that the efficiencies of the black hole heat engines can be influenced by both the size of the benchmark circular cycle and the cosmic string tension as a thermodynamic variable. In general, the efficiency can be increased by enlarging the cycle, but is still constrained by a universal bound 2pi /(pi +4) as expected. A cross-comparison of the efficiencies of the accelerating black hole heat engines and Schwarzschild-AdS black hole heat engines suggests that the acceleration also increases the efficiency although the amount of increase is not remarkable.

Analysis of Hole Taper, Recast Layer and Heat Affected zone in pulsed O2 and N2 laser drilling of Difficult-to-cut alloy Nimonic C-263

The quality and performance of the drilled component is of prime importance in the development of aero-engine components and are directly related to the quality of HAZ, Recast Layer and Hole taper. In order to maintain and/or improve the reliability of aerospace components, it is first essential to be aware of the possible damages that can be imparted to a material when it is drilled. Therefore, an attempt has been taken to investigate the effect of laser drilling parameters such as Gas Type: O2, N2; Power: 3200Watts, 3900Watts and Pressure: 4 bars, 5 bars, while laser drilling the Nimonic C-263 super alloy. Laser drilling trails have been conducted with different combinations of drilling parameters. The quality of the drilled holes such as Hole Tapper, HAZ and Recast Layer were evaluated quantitatively and analyzed through scanning electron microscope (SEM).

Thermodynamic properties of charged three-dimensional black holes in the scalar-tensor gravity theory

Making use of the suitable transformation relations, the action of three-dimensional Einstein-Maxwell-dilaton gravity theory has been obtained from that of scalar-tensor modified gravity theory coupled to the Maxwell's electrodynamics as the matter field. Two new classes of the static three-dimensional charged dilatonic black holes, as the exact solutions to the coupled scalar, electromagnetic and gravitational field equations, have been obtained in the Einstein frame. Also, it has been found that the scalar potential can be written in the form of a generalized Liouville-type potential. The conserved black hole charge and masses as well as the black entropy, temperature, and electric potential have been calculated from the geometrical and thermodynamical approaches, separately. Through comparison of the results arisen from these two alternative approaches, the validity of the thermodynamical first law has been proved for both of the new black hole solutions in the Einstein frame. Making use of the canonical ensemble method, a black hole stability or phase transition analysis has been performed. Regarding the black hole heat capacity, with the black hole charge as a constant, the points of type-1 and type-2 phase transitions have been determined. Also, the ranges of the black hole horizon radius at which the Einstein black holes are thermally stable have been obtained for both of the new black hole solutions. Then making use of the inverse transformation relations, two new classes of the string black hole solutions have been obtained from their Einstein counterpart. The thermodynamics and thermal stability of the new string black hole solutions have been investigated. It has been found that thermodynamic properties of the new charged black holes are identical in the Einstein and Jordan frames.

Thermodynamics of charged dilatonic BTZ black holes in rainbow gravity

In this paper, the charged three-dimensional Einstein's theory coupled to a dilatonic field has been considered in the rainbow gravity. The dilatonic potential has been written as the linear combination of two Liouville-type potentials. Four new classes of charged dilatonic rainbow black hole solutions, as the exact solution to the coupled field equations of the energy dependent space time, have been obtained. Two of them are correspond to the Coulomb's electric field and the others are consequences of a modified Coulomb's law. Total charge and mass as well as the entropy, temperature and electric potential of the new charged black holes have been calculated in the presence of rainbow functions. Although the thermodynamic quantities are affected by the rainbow functions, it has been found that the first law of black hole thermodynamics is still valid for all of the new black hole solutions. At the final stage, making use of the canonical ensemble method and regarding the black hole heat capacity, the thermal stability or phase transition of the new rainbow black hole solutions have been analyzed.

Nonlinearly charged black holes in the scalar-tensor modified gravity theory

Starting from the action of the scalar-tensor modified gravity theory coupled to the power law nonlinear electrodynamics and making use of the suitable transformation relations, the corresponding action of the Einstein-power-Maxwell-dilaton gravity theory has been obtained. Thermodynamical properties of the new charged dilatonic black holes have been investigated in the presence of a power Maxwell field as the nonlinear electrodynamics. Making use of a special form of a scalar field, it has been found that the scalar potential can be written as the linear combination of three Liouville-type potentials. Three new classes of spherically symmetric charged dilatonic black hole solutions have been obtained as the exact solutions to the field equations of the Einstein-power-Maxwell-dilaton theory. The conserved and thermodynamical quantities, related to the new black hole solutions, have been calculated from geometrical and thermodynamical approaches separately. Through comparison of the results obtained from these two alternative approaches, the validity of the first law of black hole thermodynamics has been confirmed for either of three new black hole solutions. Thermal stability or phase transition of the new black hole solutions has been analyzed, making use of the canonical ensemble method, and by calculating the black hole heat capacity at the fixed black hole charge. The points of type one and type two phase transitions as well as the ranges at which the black holes are locally stable have been determined precisely. The nonlinearly charged string black hole solutions have been obtained from their Einstein's counterparts. The thermodynamical properties as well as the thermal stability of the new charged string black holes have been investigated by utilizing the canonical ensemble method.

Black hole thermodynamics and heat engines in conformal gravity

The extended phase-space thermodynamics and heat engines for static spherically symmetric black hole solutions of four-dimensional conformal gravity are studied in detail. It is argued that the equation of states (EOS) for such black holes is always branched, any continuous thermodynamical process cannot drive the system from one branch of the EOS into another branch. Meanwhile, the thermodynamical volume is bounded from above, making the black holes always super-entropic in one branch and may also be super-entropic in another branch in certain range of the temperature. The Carnot and Stirling heat engines associated to such black holes are shown to be distinct from each other. For rectangular heat engines, the efficiency always approaches zero when the rectangle becomes extremely narrow, and given the highest and lowest working temperatures fixed, there is always a maximum for the efficiency of such engines.

Ultrafast Silicon Photonics with Visible to Mid-Infrared Pumping of Silicon Nanocrystals.

Dynamic optical control of infrared (IR) transparency and refractive index is achieved using boron-doped silicon nanocrystals excited with mid-IR optical pulses. Unlike previous silicon-based optical switches, large changes in transmittance are achieved without a fabricated structure by exploiting strong light coupling of the localized surface plasmon resonance (LSPR) produced from free holes of p-type silicon nanocrystals. The choice of optical excitation wavelength allows for selectivity between hole heating and carrier generation through intraband or interband photoexcitation, respectively. Mid-IR optical pumping heats the free holes of p-Si nanocrystals to effective temperatures greater than 3500 K. Increases of the hole effective mass at high effective hole temperatures lead to a subpicosecond change of the dielectric function, resulting in a redshift of the LSPR, modulating mid-IR transmission by as much as 27%, and increasing the index of refraction by more than 0.1 in the mid-IR. Low hole heat capacity dictates subpicosecond hole cooling, substantially faster than carrier recombination, and negligible heating of the Si lattice, permitting mid-IR optical switching at terahertz repetition frequencies. Further, the energetic distribution of holes at high effective temperatures partially reverses the Burstein-Moss effect, permitting the modulation of transmittance at telecommunications wavelengths. The results presented here show that doped silicon, particularly in micro- or nanostructures, is a promising dynamic metamaterial for ultrafast IR photonics.

Thermodynamics of ( 2+1 )-dimensional black holes in Einstein-Maxwell-dilaton gravity

In this paper, the linearly charged three-dimensional Einstein's theory coupled to a dilatonic field has been considered. It has been shown that the dilatonic potential must be considered in a form of generalized Liouville-type potential. Two new classes of charged dilatonic black hole solutions, as the exact solutions to the Einstein-Maxwell-dilaton (EMd) gravity, have been obtained and their properties have been studied. The conserved charge and mass related to both of the new EMd black holes have been calculated. Through comparison of the thermodynamical extensive quantities (i.e., temperature and entropy) obtained from both, the geometrical and the thermodynamical methods, the validity of first law of black hole thermodynamics has been investigated for both of the new black holes we just obtained. At the final stage, making use of the canonical ensemble method and regarding the black hole heat capacity, the thermal stability or phase transition of the new black hole solutions have been analyzed. It has been shown that there is a specific range for the horizon radius in such a way that the black holes with the horizon radius in that range are locally stable. Otherwise, they are unstable and may undergo type one or type two phase transitions to be stabilized.

Thermodynamics of novel charged dilatonic BTZ black holes

In this paper, the three-dimensional Einstein–Maxwell theory in the presence of a dilatonic scalar field has been studied. It has been shown that the dilatonic potential must be considered as the linear combination of two Liouville-type potentials. Two new classes of charged dilatonic BTZ black holes, as the exact solutions to the coupled scalar, vector and tensor field equations, have been obtained and their properties have been studied. The conserved charge and mass of the new black holes have been calculated, making use of the Gauss's law and Abbott–Deser proposal, respectively. Through comparison of the thermodynamical extensive quantities (i.e. temperature and entropy) obtained from both, the geometrical and the thermodynamical methods, the validity of the first law of black hole thermodynamics has been confirmed for both of the new black holes we just obtained. A black hole thermal stability or phase transition analysis has been performed, making use of the canonical ensemble method. Regarding the black hole heat capacity, it has been found that for either of the new black hole solutions there are some specific ranges in such a way that the black holes with the horizon radius in these ranges are locally stable. The points of type one and type two phase transitions have been determined. The black holes, with the horizon radius equal to the transition points are unstable. They undergo type one or type two phase transitions to be stabilized.

Heat engine in the three-dimensional spacetime

We define a kind of heat engine via three-dimensional charged BTZ black holes. This case is quite subtle and needs to be more careful. The heat flow along the isochores does not equal to zero since the specific heat CV ≠ 0 and this point completely differs from the cases discussed before whose isochores and adiabats are identical. So one cannot simply apply the paradigm in the former literatures. However, if one introduces a new thermodynamic parameter associated with the renormalization length scale, the above problem can be solved. We obtain the analytical efficiency expression of the three-dimensional charged BTZ black hole heat engine for two different schemes. Moreover, we double check with the exact formula. Our result presents the first specific example for the sound correctness of the exact efficiency formula. We argue that the three-dimensional charged BTZ black hole can be viewed as a toy model for further investigation of holographic heat engine. Furthermore, we compare our result with that of the Carnot cycle and extend the former result to three-dimensional spacetime. In this sense, the result in this paper would be complementary to those obtained in four-dimensional spacetime or ever higher. Last but not the least, the heat engine efficiency discussed in this paper may serve as a criterion to discriminate the two thermodynamic approaches introduced in ref. [29] and our result seems to support the approach which introduces a new thermodynamic parameter R = r0.

Thermodynamics of (2+1)-dimensional charged black holes with power-law Maxwell field

In this work, the three-dimensional nonlinearly charged black holes have been considered with a power-law modified electromagnetic theory. The black hole solutions to Einstein's three-dimensional field equations with a negative cosmological constant have been constructed in the presence of power-law nonlinear electrodynamics. Through the physical and mathematical interpretation of the solutions, a new class of asymptotically anti--de Sitter (AdS) black hole solutions has been introduced. The area law, surface gravity, and Gauss's law are utilized to obtain the entropy, temperature, and electric charge of the new AdS black holes, respectively. The quasilocal mass of the solutions has been calculated based on the counterterm method. A Smarr-type formula for the mass as a function of entropy and charge has been obtained. It has been shown that the thermodynamical quantities satisfy the first law of thermodynamics for the new AdS black holes. Also, it has been found that in order for the Smarr mass formula to be compatible with the first law of black hole thermodynamics, the cosmological parameter $\mathrm{\ensuremath{\Lambda}}$ should be treated as a thermodynamical variable and the generalized first law of thermodynamics has been introduced. Through the canonical ensemble method, the black hole remnant or phase transitions have been investigated regarding the black hole heat capacity. It has been found that the AdS black hole solutions we just obtained are thermodynamically stable.

Sub-Picosecond Auger-Mediated Hole-Trapping Dynamics in Colloidal CdSe/CdS Core/Shell Nanoplatelets.

Quasi-two-dimensional colloidal nanoplatelets (NPLs) have recently emerged as a class of semiconductor nanomaterials whose atomically precise monodisperse thicknesses give rise to narrow absorption and emission spectra. However, the sub-picosecond carrier dynamics of NPLs at the band edge remain largely unknown, despite their importance in determining the optoelectronic properties of these materials. Here, we use a combination of femtosecond transient absorption spectroscopy and nonadiabatic molecular dynamics simulations to investigate the early time carrier dynamics of CdSe/CdS core/shell NPLs. Band-selective probing reveals sub-picosecond Auger-mediated trapping of holes with an effective second-order rate constant of 3.5 ± 1.0 cm2/s. Concomitant spectral blue shifts that are indicative of Auger hole heating are found to occur on the same time scale as the sub-picosecond trapping dynamics, whereas spectral red shifts that emerge at low excitation densities furnish an electron-cooling time scale of 0.84 ± 0.09 ps. Finally, nonadiabatic molecular dynamics simulations relate the observed sub-picosecond Auger-mediated hole-trapping dynamics to a shallow trap state that originates from the incomplete passivation of dangling bonds on the NPL surface.

Development of a Bitter-Type Magnet System

A 10-T water-cooled Bitter-type magnetic system is under development at the Dusty Plasma Laboratory of the University of Maryland, Baltimore County. We present here methods used for preliminary magnet designs, which include minimizing ohmic heating and placement of water-cooling holes on current-carrying resistive Bitter conductors. Subsystems, such as the pressure vessel and vacuum chamber, motivate the coil design. The proposed power and cooling water delivery subsystems that drive and cool the magnet are also presented. A finite-element analysis is conducted on the proposed water delivery system. A one-tenth magnetic field scale-model of the magnet is currently being constructed. Upon completion and testing of the prototype magnet system, the large-scale model will be produced. Planned experiments include the propagation of magnetized waves in dusty plasma under various boundary and rotational shear flow conditions, among others in a 10-T field on a timescale of at least 10 s.

An Exact Efficiency Formula for Holographic Heat Engines

Further consideration is given to the efficiency of a class of black hole heat engines that perform mechanical work via the pdV terms present in the First Law of extended gravitational thermodynamics. It is noted that, when the engine cycle is a rectangle with sides parallel to the (p,V) axes, the efficiency can be written simply in terms of the mass of the black hole evaluated at the corners. Since an arbitrary cycle can be approximated to any desired accuracy by a tiling of rectangles, a general geometrical algorithm for computing the efficiency of such a cycle follows. A simple generalization of the algorithm renders it applicable to broader classes of heat engine, even beyond the black hole context.