Boltzmann Constant Research Articles

Dissipative split-charge formalism: Ohm's law, Nyquist noise, and non-contact friction.

The split-charge equilibration method is extended to describe dissipative charge transfer similarly as the Drude model, whereby the complex-valued frequency-dependent dielectric permittivities or conductivities of dielectrics and metals can be mimicked at non-zero frequencies. To demonstrate its feasibility, a resistor-capacitor circuit is simulated using an all-atom representation for the resistor and capacitor. The dynamics reproduce the expected charging process and Nyquist noise, the latter resulting from the thermal voltages acting on individual split charges. The method bears promise to model friction caused by the motion of charged particles past metallic or highly polarizable media.

The Analysis of Whether India Views China as a Military Security Threat from a Quantitative Perspective

China is a neighboring major country of India. Many scholars have consistently emphasized in their papers that India regards China as its biggest military threat. If this viewpoint is fair, then India’s military defense will inevitably be influenced by China. In other words, the military defense of China and India should be highly correlated. National defense and military can be measured by two indicators: weapon throughput and the proportion of military expenditure to domestic GDP. According to the dimensionless operation and entropy weight method in quantitative analysis, the weights of two indicators can be obtained and their correlation can be analyzed. After quantitative analysis, there is a weak correlation between the military defense of China and India. So, it can be concluded that India does not fully consider China as the main military threat.

Collective dynamics and long-range order in thermal neuristor networks

In the pursuit of scalable and energy-efficient neuromorphic devices, recent research has unveiled a novel category of spiking oscillators, termed “thermal neuristors.” These devices function via thermal interactions among neighboring vanadium dioxide resistive memories, emulating biological neuronal behavior. Here, we show that the collective dynamical behavior of networks of these neurons showcases a rich phase structure, tunable by adjusting the thermal coupling and input voltage. Notably, we identify phases exhibiting long-range order that, however, does not arise from criticality, but rather from the time non-local response of the system. In addition, we show that these thermal neuristor arrays achieve high accuracy in image recognition and time series prediction through reservoir computing, without leveraging long-range order. Our findings highlight a crucial aspect of neuromorphic computing with possible implications on the functioning of the brain: criticality may not be necessary for the efficient performance of neuromorphic systems in certain computational tasks.

Printed Lateral p–n Junction for Thermoelectric Generation

Printed thermoelectric generators (TEGs) show promising potential for converting waste heat into useful electricity at a low cost but fall short of exhibiting a conversion efficiency anticipated from materials’ properties. The output power of conventionally printed TEGs in the “π‐type” geometry suffers due to low thermal voltage and low current because of high thermal and electrical contact resistance, respectively. Herein, a type of printed p–n junction TEGs (PN‐TEGs) as a possible remedy is explored. Two printed PN‐TEGs with different thicknesses are fabricated using printed p‐type Bi0.5Sb1.5Te3 and n‐type Bi2Te2.7Se0.3 materials. The PN‐TEGs show a promising way to minimize the influence of thermal and electrical resistance in printed TEGs. In the experimental and simulation results, the significant impact of PN‐TEGs’ dimensions on their power outputs is revealed. Also, a conventional “π‐type” printed TEG is fabricated and its performance is studied. The optimized PN‐TEG with a single thermocouple yields ≈14 times higher power output density of 5.3 μW cm−2 at a ΔT of 25 K compared to “π‐type” printed TEGs.

Physical interpretation of entropy, Boltzmann constant, and temperature

Through the previously reported the quantum-identity, the light-model, and the T(temperature)·\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\cdot$$\\end{document}S(entropy) energy, the implied meaning of temperature and entropy, respectively, which it was difficult to intuitively recognize, was clearly defined. In order to minimize possible errors at this time, the interrelationship of the SI base unit, which is the smallest unit, and the T(temperature)·\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\cdot$$\\end{document}S(entropy) unit integration was used. In the process of converting to Planck units, each unit (criterion) for entropy and temperature was calculated, and their physical and chemical meanings were compared and reinterpreted. Thus, the unit of entropy is related to the Boltzmann constant, and the temperature is the oscillation of pure mass units. Therefore, the intuitive recognition of physical and chemical factors based on the unit of meter(m)-time(s) is considered sufficient as an initiator to move closer to new science beyond the current limited application.

Simultaneous electrochemical reduction of water and oxidation of carbon in a solid oxide cell for separately producing hydrogen and carbon monoxide

Hydrogen can be produced from reduction of water at the cathode of a solid oxide electrolysis cell (SOEC) and electricity and CO gas can be co-generated from the oxidation of carbon at the anode of a direct carbon solid oxide fuel cell (DC-SOFC). In the present work, a solid oxide cell (SOC) combining the cathode reaction of the SOEC and the anode reaction of the DC-SOFC is proposed, prepared, and investigated. It is demonstrated that hydrogen and CO can be separately produced from the cathode and anode through simultaneous reduction of water and oxidation of carbon in such a H2O-C SOC. Resistances from electrode polarizations are analyzed through measuring current-voltage characteristics, overpotentials, and AC impedances of the cell. The advantage of the H2O-C SOC over two separately operated SOEC and DC-SOFC is verified by the resistance analysis. An electrolyte-supported H2O-C SOC, with a cermet of silver and gadolinium-doped ceria (Ag-GDC) as the symmetrical electrode material and a steam concentration of 50 % at the cathode, gives an operating current density of 0.67 A cm-2 at the thermal neutral voltage (0.7 V). It stably operates at 0.2 A cm-2 under an applied voltage of only 0.16 V, producing pure hydrogen from the cathode and CO with a concentration of 88 % from the anode. The performance is significantly improved by using an anode-supported H2O-C SOC which gives an operating current density of 2.27 A cm-2 at the thermal neutral voltage.

Utilization of coconut shell activated carbon to generate electrical energy using sodium chloride electrolyte

Fossil fuels that are used to generate electrical energy are running low. Besides that, energy generated from fossil fuels causes global warming and climate change due to gas emissions such as carbon dioxide, leading to a greenhouse effect. In addition, the development of small electronic devices has created power demands, from initially in milli watt (mW), to microwatt (μW) level for wireless sensor networks, which generally use batteries as a power supply. Therefore, environmentally friendly and renewable materials like coconut shells are needed to generate electrical energy. This research aims to generate electrical energy from a model using coconut shell activated carbon with sodium chloride (NaCl) electrolyte. The electrical energy generation model is composed of counter electrode–electrode–counter electrode. The electrode used was coconut shell–activated carbon. Three counter electrodes were used: aluminum, zinc and copper plates. The electrolyte used was sodium chloride (NaCl) solution. The electrolyte was injected between the electrode and the counter electrode, and heat was applied. When the electrolyte was injected into the electrical energy generation model, interaction occurred between the ions from the electrolyte and the functional groups, the pores of the activated carbon, and the counter electrode, and then electrons were released. The research results show that the voltage produced due to an increase in temperature up to ΔT=54 °C, is 0.875 volts for aluminum, 0.767 volts for zinc and 0.091 volts for copper. The average thermal voltage sensitivity (dV/dT) for aluminum is 68.99297 mV/°C, while that for zinc is 61.34319 mV/°C, and copper is 7.02533 mV/°C. The currents produced by aluminum, zinc and copper are 5.9 μA, 3.8 μA and 0.157 μA, respectively

Thermorechargeable battery composed of mixed electrodes

A thermorechargeable battery (TB) can be charged by heating or cooling, and hence, converts thermal energy into electric energy. The manufacture of TB, however, requires adjustment of the cathode and anode potentials by pre-oxidation. Here, we demonstrated that application of mixed electrodes composed of reduced and oxidized compounds makes the adjustment process unnecessary. The TB made of mixed electrodes exhibited excellent thermal cycle stability of the thermal voltage VTB and discharge capacity QTB between 20 °C and 50 °C.

Spin-Correlated Luminescence of a Carbazole-Containing Diradical Emitter: Single-Molecule Magnetoluminescence and Thermally Activated Emission.

Luminescent radicals have been intensively studied as a new class of materials exhibiting novel photofunctions unique to open-shell systems. When luminescent radicals are assembled, intriguing spin-correlated luminescence phenomena emerge, including excimer-like emission and magnetic-field effects on luminescence (i.e., magnetoluminescence, MagLum). However, the underlying mechanisms of these phenomena arising from spin multiplicity and spin-dependent excited-state dynamics are poorly understood due to the limited number of luminescent polyradical systems available for study. In particular, the correlation between stronger intramolecular exchange interactions (|2J/kB| > ∼10 K, where J and kB are the intramolecular exchange coupling constant and the Boltzmann constant, respectively) and luminescence properties has not been fully explained. In this study, a novel carbazole-containing diradical emitter (1) and the corresponding monoradical (2) were prepared for the in-depth study of spin-correlated luminescence properties, with luminescence measurements under magnetic fields of up to 18 T. Diradical 1 has a negative 2J/kB value of several tens of kelvin and exhibits a single-molecule MagLum and thermally activated luminescence, whereas 2 does not. Detailed quantitative analyses revealed that both the spin-correlated luminescence properties of 1 are strongly dominated by ground-state spin statistics based on the Boltzmann distribution (i.e., 2J/kB values). Furthermore, diradical 1 exhibits external heavy-atom effects in heavy-atom-containing solvents such as iodobenzene, whereas monoradical 2 does not. This is the first experimental verification of external heavy-atom effects in polyradical emitters. This work demonstrates that polyradical emitters can be designed based on spin degrees of freedom in both ground and excited states.

Lifetime reliability modeling on EMC performance of digital ICs influenced by the environmental and aging constraints: A case study

This paper aims to develop the lifetime reliability model on electromagnetic compatibility (EMC) performance of the Atmel Attiny85 microcontroller integrated circuit (IC) chip samples, depending on the observed variation of the conducted immunity to the electromagnetic interference imposed by the combined influence of various environmental and aging (i.e., thermal and electrical voltage stress) constraints. A constant-stress accelerated degradation tests plan was designed and implemented by applying different constant thermal (i.e., 70 and 110 °C) and electrical voltage (i.e., 4 and 5 V) stress magnitude levels simultaneously in various multiple stress combinations. Direct power injection (DPI) conducted immunity tests were performed in nominal condition on all the programmed device under test (DUT) samples in both the fresh and aged states at various stress time duration. The best-fit EMC degradation paths were generated using regression analysis, followed by evaluating the pseudo time-to-failure (TTF) data and estimating the unknown parameters of the developed degradation path model. The performance metrics for lifetime reliability were evaluated by combining the Weibull distribution function with the generalized Eyring accelerated life test model. The maximum likelihood estimation method was utilized to estimate the relevant reliability model parameters. The developed reliability model was found to have the capability to estimate the electromagnetic unreliability against the lifetime TTF data of all the selected DUT samples with good precision and acceptable accuracy in both nominal and aging stress conditions. It is demonstrated that the non-failure probability of the DUT samples would remain at 1 for the first 1200 h, and that, under nominal conditions, the prediction of corresponding TTF data for all of those IC samples would fluctuate between 1400 and 1600 h.

Classical and quantum thermodynamics described as a system-bath model: The dimensionless minimum work principle.

We formulate a thermodynamic theory applicable to both classical and quantum systems. These systems are depicted as thermodynamic system-bath models capable of handling isothermal, isentropic, thermostatic, and entropic processes. Our approach is based on the use of a dimensionless thermodynamic potential expressed as a function of the intensive and extensive thermodynamic variables. Using the principles of dimensionless minimum work and dimensionless maximum entropy derived from quasi-static changes of external perturbations and temperature, we obtain the Massieu-Planck potentials as entropic potentials and the Helmholtz-Gibbs potentials as free energy. These potentials can be interconverted through time-dependent Legendre transformations. Our results are verified numerically for an anharmonic Brownian system described in phase space using the low-temperature quantum Fokker-Planck equations in the quantum case and the Kramers equation in the classical case, both developed for the thermodynamic system-bath model. Thus, we clarify the conditions for thermodynamics to be valid even for small systems described by Hamiltonians and establish a basis for extending thermodynamics to non-equilibrium conditions.

Wideband AC Voltage Standards

This article presents a critical review and comparison of constructions and metrological properties of contemporary wideband standards for AC voltage. It focuses on selected thermal voltage converters (TVCs) used in alternating current-direct current (AC-DC) transfer voltage standards and for the most precise measurements of AC voltages up to approximately 100 MHz. These devices serve as primary AC voltage standards at National Measurement Institutes (NMIs).

Battery resistance and its effects on performance of laminate film-type Co-PBA/Ni-PBA tertiary battery

A tertiary battery (TB) can be charged by heating or cooling via the difference in the electrochemical Seebeck coefficient α between the cathode and anode. Here, we investigated the battery resistance R and its effect on the performance of a laminate film-type Na1.48Co[Fe(CN)6]0.87 (Co-PBA)/Na1.76Ni[Fe(CN)6]0.94 (Ni-PBA) TB. We found that the charge-transfer resistance R ct and diffusion resistance R dif are the dominant components of R, while the solution resistance R s has a minor role. Regardless of the solute type, R varied inversely proportional to the Na+ concentration M. In a high-R TB, the thermal voltage V TB and discharge capacity Q TB per unit weight of the total active material are significantly suppressed, which is quantitatively explained in terms of the voltage drop (IR, where I is current) during the discharge process.

Heat Transfer and Entropy Generation for Mixed Convection of Al2O3–Water Nanofluid in a Lid-Driven Square Cavity with a Concentric Square Blockage

The present numerical investigation is focused on analyzing the characteristics of steady laminar mixed convection flow in a lid-driven square cavity, specifically considering the utilization of Al2O3–water nanofluid. The Al2O3–water nanofluid is assumed to be Newtonian and incompressible. Within the cavity, a square blockage is positioned at its center, which is subjected to isothermal heating. The blockage ratio of the square is B = 1/4, and the Grashof number is Gr = 100. The walls of the cavity are maintained at a constant temperature, Tc, while the square blockage remains at a constant temperature, Th. The primary objective of this study is to investigate the flow and heat transfer mechanisms, as well as the entropy generation within the cavity. This investigation is conducted for a range of Richardson numbers (0.01 ≤ Ri ≤ 100) and volume fractions of the nanofluid (0 ≤ ϕ ≤ 0.05). Several parameters are obtained and analyzed, including streamlines, isotherms, velocity variations on the vertical and horizontal midplanes, local Nusselt number variations on the surfaces of the square blockage, the average Nusselt number on the square blockage, and the total dimensionless entropy generation of the system. The results of the investigation revealed that both the average Nusselt number on the square blockage and the total dimensionless entropy generation of the system exhibit an increasing trend with an increasing volume fraction of the nanofluid and a decreasing Richardson number. Furthermore, correlations for the average Nusselt number and the total dimensionless entropy generation with the Richardson number, and the nanofluid volume fraction are derived.

A novel ballistic model for the subthreshold behavior of nanosheet transistors

A novel ballistic model for the subthreshold current of nanosheet transistors is successfully developed based on the Landauer approach with the three-dimensional number of channels. The ballistic threshold voltage can also be achieved through the calculated free charge density induced by the three-dimensional density-of-states equal to the substrate doping concentration. It indicates that under the low drain voltage corresponding to the Fermi distribution function, the subthreshold current is mainly governed by the low contact potential. However, under the high drain voltage corresponding to the Fermi distribution function, the thermal voltage, instead of the contact potential between the source and drain, initiates the subthreshold current. Besides subthreshold current and threshold voltage, the ballistic conductance and subthreshold swing are also revealed in the subthreshold conduction. It indicates that the thin silicon, thin gate oxide, heavy substrate doping density, and high work function will alleviate the ballistic effects, decrease the subthreshold current/swing, and increase the threshold voltage/ballistic resistance.

Study on the characteristics of thermal runaway expansion force of LiNi0.5Co0.2Mn0.3O2/graphite lithium-ion batteries with different SOCs

In recent years, lithium-ion batteries have been widely adopted by the automotive industry because of their high energy density and environmentally friendly nature. However, the thermal runaway of lithium-ion batteries poses a significant risk of explosions, fires, and other hazards. Therefore, it is crucial to have effective thermal runaway warning systems to enhance the safety of battery applications. Currently, the main warning signals for thermal runaway include voltage, temperature, internal resistance, gas composition, and smoke. However, these signals suffer from issues such as low accuracy and delayed warnings. During thermal runaway, voltage, temperature, internal resistance, expansion force, and smoke undergo abnormal changes at varying times, with expansion force abnormalities detected notably earlier. To improve the accuracy and timeliness of thermal runaway warnings, it is crucial to quantitatively measure the changes in expansion force and signal progression related to voltage and temperature during thermal runaway through experiments. In this study, the 51 Ah LiNi0.5Co0.2Mn0.3O2/Graphite commercialized Li-ion batteries were used to study the characteristics of thermal runaway expansion force at different states of charge (SOCs) (25%, 50%, 100%, 110%). The variation patterns of thermal runaway parameters such as temperature, voltage, internal resistance, expansion force, and flame were analyzed. The test results indicate that the expansion force in lithium-ion batteries is related to the lithium-ion concentration in the negative electrode and remains below 2000 N with a rate of change under 1.8 N/s during normal charging and discharging. However, it surpasses 5000 N for thermal runaway. This paper suggests using a 2000 N expansion force as an early warning signal for thermal runaway, which precedes approximately 11.6 s earlier than the voltage signal and 10 s earlier than the internal resistance and temperature signals. Adopting a 1.8 N/s growth rate can further enhance warning time, issuing alerts 134.2 s before thermal runaway. Research confirms that using expansion force as the main signal significantly improves warning time and alarm accuracy in lithium-ion battery safety.

Quantum counterpart of equipartition theorem in quadratic systems

The equipartition theorem is a fundamental law of classical statistical physics, which states that every degree of freedom contributes kBT/2 to the energy, where T is the temperature and kB is the Boltzmann constant. Recent studies have revealed the existence of a quantum version of the equipartition theorem. In the present work, we focus on how to obtain the quantum counterpart of the generalized equipartition theorem for arbitrary quadratic systems in which the multimode Brownian oscillators interact with multiple reservoirs at the same temperature. An alternative method of deriving the energy of the system is also discussed and compared with the result of the quantum version of the equipartition theorem, after which we conclude that the latter is more reasonable. Our results can be viewed as an indispensable generalization of recent works on a quantum version of the equipartition theorem. Published by the American Physical Society 2024

High Seebeck Coefficient Thermally Chargeable Supercapacitor with Synergistic Effect of Multichannel Ionogel Electrolyte and Ti3C2Tx MXene‐Based Composite Electrode

Thermally chargeable supercapacitors can collect low‐grade heat generated by the human body and convert it into electricity as a power supply unit for wearable electronics. However, the low Seebeck coefficient and heat‐to‐electricity conversion efficiency hinder further application. In this paper, we designed a high‐performance thermally chargeable supercapacitor device composed of ZnMn2O4@Ti3C2Tx MXene composites (ZMO@Ti3C2Tx MXene) electrode and UIO‐66 metal–organic framework doped multichannel polyvinylidene fluoridehexafluoro‐propylene ionogel electrolyte, which realized the thermoelectric conversion and electrical energy storage at the same time. This thermally chargeable supercapacitor device exhibited a high Seebeck coefficient of 55.4 mV K−1, thermal voltage of 243 mV, and outstanding heat‐to‐electricity conversion efficiency of up to 6.48% at the temperature difference of 4.4 K. In addition, this device showed excellent charge–discharge cycling stability at high‐temperature differences (3 K) and low‐temperature differences (1 K), respectively. Connecting two thermally chargeable supercapacitor units in series, the generated output voltage of 500 mV further confirmed the stability of devices. When a single device was worn on the arm, a thermal voltage of 208.3 mV was obtained indicating the possibility of application in wearable electronics.

A seven‐level switched‐capacitor based transformerless inverter with modified PWM strategy to enhance the performance of grid‐connected PV systems

AbstractAmong different types of transformerless photovoltaic inverters, multi‐level inverters based on switched‐capacitors (SC) are the burning topic of recent decades due to their potential advantages, such as, single source requirement, voltage boosting capability, and high power density. However, for a seven level output voltage, a conventional SC based inverter architecture uses more than two units of SC, a large amount of power switches, which then lead to capacitor voltage balancing problems. This paper presents a seven‐level switched‐capacitor transformerless inverter (SCTI), which is structured with only two SC units, ten power switches, and a single DC source. The proposed SCTI ensures voltage boosting capability, self‐voltage balancing, and low power semiconductor losses. Apart from these, a modified sinusoidal pulse width modulation (MSPWM) is also proposed in this work, which guarantees better thermal performance and low inverter output voltage THD for the proposed SCTI. The proposed SCTI along with the MSPWM is simulated in MATLAB/Simulink and PLECS computer simulation environments. A reduced scale laboratory prototype is also built and tested to ensure the feasibility of the proposed SCTI.

Structural design and performance optimization of Co/Bi0.5Sb1.5Te3 artificially tilted multilayer thermoelectric devices

Due to the complex principle of transverse thermoelectric conversion and the specific preparation technique, there are few studies on the three-dimensional structure of artificially tilted multilayer thermoelectric devices (ATMTDs), which also lags the development of ATMTDs for applications. It is necessary to optimize the three-dimensional structure of ATMTDs to satisfy the requirements of practical applications in thermal sensors, power generation, refrigeration, and so on. In this paper, Co/Bi0.5Sb1.5Te3 ATMTDs are selected as the research object. A COMSOL Multiphysics simulation analysis and experimental validation are used to establish the relationship between the structure and its thermal sensing, power generation, and cooling performance. Results indicate that increasing the length significantly improves the thermal response voltage. Increasing the length and width enhances output power while increasing the height of the ATMTD improves the thermoelectric conversion efficiency. The effective cooling temperature improves when the heat transfer area decreases or the height increases. Based on these findings, flexible thin-film thermal sensors, high-efficiency waste heat power generation tubular devices, and high-efficiency refrigeration pyramidal devices are designed. The results will lead to effective optimization and promote the multi-field application of ATMTDs.