A CFD modeling of CPU cooling by eco-friendly nanofluid and fin heat sink passive cooling techniques

In this research, a three-dimensional (3D) Computational Fluid Dynamics (CFD) model-based Finite Volume Method (FVM) is performed to study the influence of single-phase green graphene/water nanofluid and two designs (snaky and sinusoidal spiral) of fin on the thermal management of a CPU in the electronic package. The thermophysical properties of eco-friendly nanofluid described by User Defined Function (UDF) code in ANSYS-Fluent 2021 R2 package. Besides the fin design, the impact of heat sink’s (fin and solid block) materials (silver, copper, and nickel), and the variations of nanoparticles volume fraction on the CPU cooling, pressure changes, pumping power, convective heat transfer coefficient, and thermal efficiency of fin heat sink have been investigated. Outcomes indicate that the sinusoidal spiral fin design is more efficient than the snaky-one. The number of sine arcs on the fins has a direct relationship with the heat transfer rate and an inverse relationship with the pressure changes. Because of the higher thermal conductivity of silver, the silver heat sink is more efficient than the copper and nickel heat sinks for CPU cooling. Increasing the wavelength of spiral and snaky fins led to a $7,11.5K$ temperature reduction in the center of the liquid block heat sink. Additionally, the best thermal performance of liquid block heat sink is about $6.82\%$ related to the nanofluid with a concentration of $\phi =0.100\%$, while it is about $6.83\%$ for the nanofluid with a concentration of $\phi =0.075\%$.     

Study on decolorization of Rhodamine B by raw coal fly ash catalyzed Fenton-like process under microwave irradiation

Coal fly ash (CFA) catalyzed Fenton-like process was studied under microwave (MW) irradiation for the decolorization of Rhodamine B (RhB) wastewater. The physical-chemical properties of CFA were characterized, including the specific surface area, micromorphology, chemical and crystal components, and the distribution and chemical valence of metallic elements. The metallic oxidants in the CFA indicate CFA can work as Fenton-like catalyst and MW-absorbent simultaneously. The results reveal OH is more significant in the decolorization of RhB than HO₂ and O₂^?. The generation of more OH in the MW-Fenton-like process (293–326 K) than that in the conventional heated Fenton-like process (326 K) reflects the function of hot spot effect and possible non-thermal effect of MW. Under the optimum condition ([H₂O₂] 2 mmol L^?1, [CFA] 15 g L^?1, pH 3, P_MW 0.1 kW), the decolorization rate reaches 91.6% after 20 min. The intrinsic kinetic model of RhB decolorization is $-\frac{\mathrm{d}{C}_{\mathrm{R}\mathrm{h}\mathrm{B}}}{\mathit{dt}}={1.76\times 10}^{-4}·C_{\mathrm{R}\mathrm{h}\mathrm{B}}·C_{{\mathrm{H}}_2{\mathrm{O}}_2}^{1.89}·C_{\mathrm{C}\mathrm{F}\mathrm{A}}^{1.97}-\mathrm{d}{\mathrm{C}}_{\mathrm{R}\mathrm{h}\mathrm{o}\mathrm{d}\mathrm{a}\mathrm{m}\mathrm{i}\mathrm{n}\mathrm{e}\mathrm{B}}/\mathrm{d}\mathrm{t}=1.76\times {10}^{-4}·{\mathrm{C}}_{\mathrm{R}\mathrm{h}\mathrm{o}\mathrm{d}\mathrm{a}\mathrm{m}\mathrm{i}\mathrm{n}\mathrm{e}\mathrm{B}}·{\mathrm{C}}_{{\mathrm{H}}_2{\mathrm{O}}_2}^{1.89}·{\mathrm{C}}_{\mathrm{c}\mathrm{o}\mathrm{a}\mathrm{l}\mathrm{f}\mathrm{l}\mathrm{y}\mathrm{a}\mathrm{s}\mathrm{h}}^{1.97}$. The loss of catalytic metallic elements causes the decline of catalytic capacity of CFA. The energy consumption (4313.3 kW·h kg^?1 RhB) is a limitation for the MW-Fenton-like process, which can be overcame by the safe application of nuclear energy. The intermediates and the path of RhB decolorization were detected and proposed, respectively.     

High-energy photon beam production with laser-Compton backscattering

We have produced a beam of high-energy gamma-rays by Compton backscattering of $\text{1064}\text{nm}$ laser photons from 1 GeV electrons circulating in a storage ring. Measuring the energy spectra of the backscattering photons with an HPGe detector, we have found that the maximum energy of $\text{17.6}\text{MeV}$ and the measured energy spectra show agreement with the simulation calculations, while the detected photon yields were measured at about 4×10³, 2×10³ and $\text{3×10}{}^2\text{photons}\text{s}{}^{\mathrm{-1}}\text{mA}{}^{\mathrm{-1}}\text{W}{}^{\mathrm{-1}}$ for the 20, 10 and $\text{2}\text{mm}\text{φ}$ collimators, respectively. The photon energy widths from the collimators correspond to 6.6–$\text{17.6}\text{MeV}$, 12.4–$\text{17.6}\text{MeV}$ and 17.3–$\text{17.6}\text{MeV}$, respectively. By using these photons, we measured the total nuclear photoabsorption cross-sections in the E1 giant resonance energy region for ${}^{197}\text{Au}$ using the attenuation method and we have demonstrated that the photon attenuation method will be a useful tool for studying photonuclear reactions.     

π/p separation at 1.2GeV/c by an emulsion cloud chamber

We have performed an experimental study of π/p separation at a momentum of $\text{1.2}\text{GeV}\text{/}\text{c}$ using an Emulsion Cloud Chamber (ECC) detector with secondary beam produced by the proton synchrotron at KEK. The separation is greater than 3 standard deviations using dE/dx measurements of $\text{2.6}\text{mm}$ long tracks with an automatic emulsion read-out system.     

A compact planar positron imaging system

A planar imaging system for positron-emitting radiotracers was developed and its physical performance was evaluated. The new device consists of two opposing planar detectors, each having 4 (columns) $\text{×}\text{6}$ (rows) detector units, and each unit composed of 10×10 arrays of $\text{2×2×20}\text{mm}{}^3$ pillars of Bi₄Ge₃O₁₂ (BGO) scintillators and a metal-packaged position-sensitive photomultiplier tube. The system is very compact and has a simple structure that allows versatile positioning of detectors in the horizontal or vertical mode. Focal plane images are constructed from coincidence data collected by opposing planar detectors. The system provides good quality images even in a short period of time or with low tracer activity. Spatial resolutions of 1.6–$\text{2.1}\text{mm}$ FWHM were achieved for the entire field of view. The sensitivity was $\text{107}\text{cps}\text{/}\text{kBq}\text{/}\text{ml}$ measured in a uniform flat phantom. In this study, the capability of the new system was demonstrated by the imaging of radiotracer distribution in rats and plants.     

Data acquisition and monitoring for the KLOE detector

The Data Acquisition system for the KLOE experiment, presently running at the Laboratori Nazionali di Frascati DAΦNE collider, has been designed to sustain an acquisition throughput of $\text{50}\text{Mbyte}\text{/}\text{s}$ for an event rate of $\text{10}\text{kHz}$. Its two major components are the front end data readout, based on custom buses, and a complex network of computers and storage devices hosting a set of distributed processes. The end result is a seamless data transport from the readout system to the storage library, accompanied by concurrent on line calibrations and data quality control.