bluuebunny/crossref_metadata_2025 huggingface dataset:
Stochastic dynamics of multi-waterfall hybrid inflation and formation of primordial black holes
Authors: Tada Yuichiro , Yamada Masaki
Published: November 2023

We show that a hybrid inflation model with multiple waterfall fields can result in the
formation of primordial black holes (PBHs) with an astrophysical size, by using an advanced algorithm to follow the
stochastic dynamics of the waterfall fields. This is in contrast to the case with a single
waterfall field, where the wavelength of density perturbations is usually too short to form PBHs
of the astrophysical scale (or otherwise PBHs are overproduced and the model is ruled out)
unless the inflaton potential is tuned. In particular, we demonstrate that PBHs with masses of
order 1020 g can form after hybrid inflation consistently with other cosmological
observations if the number of waterfall fields is about 5 for the case of instantaneous
reheating. Observable gravitational waves are produced from the second-order effect of large
curvature perturbations as well as from the dynamics of texture or global defects that form after
the waterfall phase transition.
Spectra of axions emitted from main sequence stars
Authors: Nguyen Ngan H. , Tanin Erwin H. , Kamionkowski Marc
Published: November 2023

We compute the detailed energy spectra of axions with two-photon coupling produced in
stellar cores over a wide range of stellar masses. We focus on main sequence stars and base our
calculations on the stellar interior profiles from MESA, for which we provide simple fits in an
appendix. The obtained stellar axion spectra, combined with recent models of star formation
history and stellar initial mass function, enable us to estimate the properties of the diffuse
axion background sourced by all the stars in the universe. The fluxes of this stellar axion
background and its decay photons are subdominant to but can in principle be disentangled from
those expected from the Sun and the early universe based on their different spectral and spatial
profiles.
Disassociation of a one-dimensional cold molecule via quantum scattering
Authors: Li Wen-Liang , Song Hai-Jing , Song Tie-Ling , Zhou D L
Published: November 2023

Motivated by the recent experimental developments in ultracold molecules and atoms, we propose a simple theoretical model to address the disassociation, reflection, and transmission probability of a one-dimensional cold molecule via quantum scattering. First, we show the Born approximation results in the weak interaction regime. Then, by employing the Lippmann–Schwinger equation, we give the numerical solution and investigate the disassociation’s dependence on the injection momentum and the interaction strengths. We find that the maximum disassociation rate has a limit when increasing the interaction strengths and injection momentum. We expect that our model can be realized in experiments in the near future.
Spatial quantum coherent modulation with perfect hybrid vector vortex beam based on atomic medium
Authors: Ma 马 Yan 燕 , Yang 杨 Xin 欣 , Chang 常 Hong 虹 , Yang 杨 Xin-Qi 鑫琪 , Cao 曹 Ming-Tao 明涛 , Zhang 张 Xiao-Fei 晓斐 , Gao 高 Hong 宏 , Dong 董 Rui-Fang 瑞芳 , Zhang 张 Shou-Gang 首刚
Published: November 2023

The perfect hybrid vector vortex beam (PHVVB) with helical phase wavefront structure has aroused significant concern in recent years, as its beam waist does not expand with the topological charge (TC). In this work, we investigate the spatial quantum coherent modulation effect with PHVVB based on the atomic medium, and we observe the absorption characteristic of the PHVVB with different TCs under variant magnetic fields. We find that the transmission spectrum linewidth of PHVVB can be effectively maintained regardless of the TC. Still, the width of transmission peaks increases slightly as the beam size expands in hot atomic vapor. This distinctive quantum coherence phenomenon, demonstrated by the interaction of an atomic medium with a hybrid vector-structured beam, might be anticipated to open up new opportunities for quantum coherence modulation and accurate magnetic field measurement.
Dark matter interactions from an extra U(1) gauge symmetry with kinetic mixing and Higgs charge*
Authors: Shan 单 Lianyou 连友 , Yu 余 Zhao-Huan 钊焕
Published: November 2023

We investigate fermionic dark matter interactions with standard model particles from an additional

gauge symmetry, assuming kinetic mixing between the

and

gauge fields as well as a nonzero

charge of the Higgs doublet. To ensure gauge-invariant Yukawa interactions and the cancellation of gauge anomalies, standard model fermions are assigned Y-sequential

charges proportional to the Higgs charge. Although the Higgs charge should be small owing to collider constraints, it is useful to decrease the effective cross section of dark matter scattering off nucleons by two orders of magnitude to easily evade direct detection bounds. After performing numerical scans in the parameter space, we find that the introduction of the Higgs charge can also enhance the dark matter relic density by at least two orders of magnitude. In the case where the resonance effect is important for dark matter freeze-out, when the observed relic density and direct detection constraints are tangled, the Higgs charge can expand physical windows to some extent by relieving the tension between the relic density and direct detection.
Investigating the Evolution of Amati Parameters with Redshift
Authors: Singh Meghendra , Singh Darshan , Lal Pandey Kanhaiya , Verma Dinkar , Gupta Shashikant
Published: November 2023

Gamma-ray bursts (GRBs) are among the brightest objects in the Universe and, hence, can be observed up to a very high redshift. Properly calibrated empirical correlations between intensity and spectral correlations of GRBs can be used to estimate the cosmological parameters. However, the possibility of the evolution of GRBs with redshift is a long-standing puzzle. In this work, we used 162 long-duration GRBs to determine whether GRBs below and above a certain redshift have different properties. The GRBs are split into two groups, and we fit the Amati relation for each group separately. Our findings demonstrate that estimations of the Amati parameters for the two groups are substantially dissimilar. We perform simulations to investigate whether the selection effects could cause the difference. Our analysis shows that the differences may be either intrinsic or due to systematic errors in the data, and the selection effects are not their true origin. However, in-depth analysis with a new data set comprised of 119 long GRBs shows that intrinsic scatter may partly be responsible for such effects.
Dual-Wavelength Q-switched Fiber Laser Generation by Incorporating 2D Materials in D-SMS Fiber Structure
Authors: Zaini M. A. Z. , Saaid N. F. F. M. , Rusdi M. F. M. , Latiff A. A. , Rahman M. F. A. , Al-Masoodi A. H. H.
Published: November 2023

We demonstrate a dual-wavelength Q-switched fiber laser generation by inserting a combination of SM-MM-SM fiber and a d-shape structure. This combination is known as D-SMS fiber. By side-polishing an SM fiber with 1-dB loss, the d-shape fiber structure is obtained. Then the d-shape SM fiber is spliced to 25 cm long MM and SM fiber to form a D-SMS fiber structure. After inserting D-SMS fiber, a stable dual-wavelength presence at 1562.8 nm and 1563.8 nm (1 nm wavelength spacing). The pulse train generates once we deposited a graphene oxide solution onto the surface of the d-shape structure. This Q-switching operation mode obtained from 45 mW to 111 mW pump power with a maximum pulse energy of 56 nJ. The repetition rate and pulse width have been recorded from 34 kHz to 55 kHz and from 10.22 µs to 6.47 µs, respectively.
Exploration of Fibre Bragg Grating for Potential Breathing Behaviour Monitoring System
Authors: Noorbahrin N. A. S. , Mohd Asseri S. N. F. , Ahmad H. , Lim K. S. , Bahari I. , Thambiratnam K. , Zulkifli M. Z.
Published: November 2023

An optical-fiber based temperature sensor for the monitoring of breathing behaviour during different physical activities is proposed and demonstrated. The proposed sensor utilizes Fiber Bragg Gratings (FBGs) to detect temperature changes in breath, which are then correlated to the breathing behaviour and thus able to profile the patient for breathing abnormalities. The proposed sensor is cost-effective and light-weight, and can be integrated into wearable devices for real-time monitoring of the patient.
Study on the mechanism of coarse grain formation of 6061 aluminium alloy forged wheels
Authors: Chen Tieqiang , Xu Shiwen , Li Meng , Liu Haifeng
Published: November 2023

The formation of coarse grains is easy to occur during the mass production of 6061 aluminium alloy forged wheels. The coarse grains and uneven grain structure will lead to the reduction and instability of the mechanical properties of the wheels, which will affect the fatigue strength, corrosion resistance and impact toughness of the wheels. In this paper, the effect of solution temperature and solution time on the coarse-grained formation of 6061 forged wheel was studied. The reasons and mechanism of coarse-grained formation were revealed by advanced materials characterization techniques such as scanning electron microscope, electron backscattering diffraction and transmission electron microscope. The results show that the deformation causes a large number of dislocation pile-up and entanglement in the grain, forming a large number of small angle sub-grains, and the heating process of sub-grains has more interfaces, which provides the driving energy for the abnormal grain growth.
Recrystallization kinetics of larger yttria particle dispersion tungsten alloy warm rolled to 50% thickness reduction
Authors: Wang K , He G Y , Zan X , Luo L M , Liu J Q , Wu Y C
Published: November 2023

Tungsten-based materials are considered one of the candidate materials for the key components (such as the first wall and diverter) of future thermonuclear fusion reactors because of their excellent properties. At high operation temperatures, restoration processes such as recovery, recrystallization and grain growth will unavoidably embrittle ductile tungsten achieved by rolling. Dispersed second-phase particles will affect the recrystallization behavior. The thermal stability of a yttria dispersion-strengthened tungsten plate warm-rolled to 50% thickness reduction is investigated. Isochronous annealing is used to predict its recrystallization temperature range and isothermal annealing is used to study its recrystallization kinetics. The tungsten alloy in the present study has a faster recrystallization kinetics and a smaller activation energy compared to that of W-2 vol% Y2O3 alloy with small Y2O3 particles, indicating that the larger Y2O3 particles have little effect on impeding grain boundaries during recrystallization.
On intergranular interaction and the crystallographic mechanism of plastically deformed polycrystalline metals
Authors: Mao Weimin
Published: November 2023

Taylor principle prevailing currently has been proved to be effective only when grains or grain clusters are deformed in a rigid environment, which disagrees with the reality. Grains realize their plastic deformation in elastoplastic environment, and the equilibrium of intergranular stress and strain need to be reached simultaneously and naturally. The intergranular reaction stress (RS) during deformation can be calculated according to Hooke’s law and the yield stress should be the up-limit of the RS. The combinations of constant external stress and changing RS in RS theory induce alternate activation of deformation systems including slips and twinning with different work hardening rates, while grain orientations and inhomogeneous distribution of external stress have important influence. Some additional deformation systems near the boundaries need to be locally activated when the reduced stress up-limits are reached frequently, to balance the intergranular stress and strain incompatibilities in elastoplastic way. Based on the simpler RS theory, the simulation results of rolling texture on aluminium, low carbon steel, austenite stainless steel, titanium are very close to the reality, indicating that the intergranular elastoplastic interactions and the corresponding crystallographic behaviours of plastic deformation have been reasonably and quantitatively described, therefore, Taylor principle becomes no more necessary.
Microstructure, texture and recrystallization of heavily rolled CoCrFeNi medium entropy alloy
Authors: Mishin O V , Xiao Y W , Cheng Z , Winther G , Wu G L , Mao X P
Published: November 2023

The microstructure and texture have been characterized in a CoCrFeNi medium entropy alloy after cold rolling to 85% and subsequent annealing at 550°C for 130 min. It is observed that the as-rolled microstructure is heterogeneous and comprises extended regions of either 〈110〉//ND or 〈111〉//ND orientations and volumes of mixed orientations. The microstructure also contains a large number of shear bands acting as preferential nucleation sites for recrystallization during annealing. Recrystallization generates annealing twins, which results in new components along the 〈110〉//ND fiber and other new orientations, thus making the texture of recrystallized regions fairly weak. Orientations demonstrating increased intensities in the recrystallization texture are identified as {113}〈332〉 and {236}〈385〉 components.
NbC reinforced FeMnCoCr high entropy alloy with excellent mechanical properties and wear resistance
Authors: Wang Q , Deng X T , Yu S X , Wang Z D
Published: November 2023

In this paper, a NbC reinforced FeMnCoCr dual-phase high entropy alloy was used. After hot rolling, cold rolling and annealing, partial recrystallization sample and fully recrystallized fine-grained sample were obtained. The annealed samples are a single FCC phase, with micron-sized NbC particles of different shapes including columnar, granular and polygonal are distributed in the matrix. The yield strength of the partial recrystallization sample is 708 MPa, which was 1.4 times of the yield strength of the fine-grained sample, and the tensile elongation is 39.4%. The main reasons for the high yield strength of partially recrystallized samples is dislocation strengthening. The recrystallization volume fraction of partially recrystallized samples is 66.2%, and the un-recrystallization grains contain high dislocation density, and the increment of dislocation strengthening is 144 MPa. The work hardening rate of partially recrystallized samples is lower than that of fine-grained samples. Due to the high dislocation density in the partially recrystallized samples, there are fewer dislocations that can be activated and propagated during the tensile process. The high yield strength and the existence of a large number of micron-sized NbC make the NbC reinforced FeMnCoCr high entropy alloy have good wear resistance.
Microstructure and texture development during annealing in UF340
Authors: Li Yi , Guan Jiandong , Ma Jiaji , Gong Jian , Wu Nai , Wei Dong , Wang Wenjun , Chen Fengjiao
Published: November 2023

UF340 is a new type of cold-rolled fine grain high-strength steel with excellent formability developed by Shougang Co., Ltd Company. In this paper, the formation mechanism of recrystallisation texture of UF340 during annealing at 720 °C were systematically investigated. The as-received cold rolled sheet displayed a pronounced α-fiber texture together with a weak γ-fiber texture. With increasing annealing time, recrystallization occurred in the elongated grains, γ-fiber texture grains generated and grew up gradually. The texture component of the original α-fiber grains shift toward {112} <110>, {023} <100>, {223}<352> and finally {111} <112>. High r-values of UF340 in all directions were achieved by the development of the remarkable γ-fiber texture. In addition, the

r
¯

value of the annealed UF340 was as high as 1.96, and the Δr value was only 0.2. As a result, excellent deep drawability and relatively high strength of UF340 were realized simultaneously, making it one of the ideal materials for automobile outer panels.
Exploring 4D microstructural evolution in a heavily deformed ferritic alloy
Authors: Yildirim Can , Detlefs Carsten , Zelenika Albert , Poulsen Henning F. , Rodriguez-Lamas Raquel , Cook Philip K. , Kutsal Mustafacan , Mavrikakis Nikolas
Published: November 2023

We present a multi-scale study of recrystallization annealing of an 85% cold rolled Fe-3%Si alloy using a combination of dark field X-ray microscopy (DFXM), synchrotron X-ray diffraction (SXRD), and electron backscatter diffraction (EBSD). The intra-granular structure of the as-deformed grain reveals deformation bands separated by ≈ 3–5°misorientation. We monitor the structural evolution of a recrystallized grain embedded in bulk, from the early stages of recrystallization to 65% overall recrystallization through isothermal annealing steps. Results show that the recrystallized grain of interest (GOI) grows much faster than its surroundings yet remains constant in size as the recrystallization proceeds. Isolated dislocations embedded within the volume of the recrystallized GOI are investigated.
Research on the modeling and control mechanism of three-phase cascade rectification stage of non-power frequency transformer
Authors: Hu Jingpeng
Published: November 2023

Non-power frequency transformers are essential and important devices for new energy generation and smart grid construction. This article analyzes the working principle of voltage cascade rectifier stage, constructs a mathematical model of three-phase cascade rectifier stage system, and simplifies its model. Finally, the idea of overall control of the voltage loop in the rectifier stage system was derived, and the traditional control method of rectification was directly transplanted into the overall control system of the cascade rectifier stage. At the same time, the characteristics of voltage loop and current loop of cascade rectifier stage system are analyzed, and the relevant control structure block diagram and controller design idea are given, which lays an important theoretical foundation for in-depth study of non-power frequency transformer.
ECG Signal Acquisition and Processing System
Authors: Chu Huiyan , Zhen Wei , Wang Hai , Wan Yuanfei
Published: November 2023

This paper mainly designs an ECG signal acquisition and processing acquisition system, which mainly includes two parts: an ECG acquisition front-end circuit module and a LabVIEW processing and display module. The front-end circuit of ECG acquisition mainly consists of amplifying and filtering modules, which are used to collect and process human signals in real time. In addition, a charging box circuit is designed at the same time, which can charge the ECG monitoring equipment while storing energy and increase the standby time of the equipment. At the same time, the acquired signal is filtered in LabVIEW, and the baseline drift is eliminated to obtain a cleaner and clearer ECG waveform.
An ascorbic acid-decorated nanostructured surface on titanium inhibits breast cancer development and promotes osteogenesis
Authors: Li Rong , Liu Hongyu , Shi Qinying , Zhang Guannan , Pang Guobao , Xu Yannan , Song Jianbo , Lu Ying
Published: November 2023

The chest wall is the most frequent metastatic site of breast cancer (BC) and the metastasis usually occurs in a solitary setting. Chest wall resection is a way to treat solitary BC metastasis, but intraoperative bone defects and local tumor recurrence still affect the life quality of patients. Titanium-based prostheses are widely used for chest wall repair and reconstruction, but their inherent bio-inertness makes their clinical performance unfavorable. Nanostructured surfaces can give titanium substrates the ability to excellently modulate a variety of cellular functions. Ascorbic acid is a potential stimulator of tumor suppression and osteogenic differentiation. An ascorbic acid-decorated nanostructured titanium surface was prepared through alkali treatment and spin-coating technique and its effects on the biological responses of BC cells and osteoblasts were assessed. The results exhibited that the nanorod structure and ascorbic acid synergistically inhibited the proliferation, spreading, and migration of BC cells. Additionally, the ascorbic acid-decorated nanostructured surface significantly promoted the proliferation and osteogenic differentiation of osteoblasts. This work may provide valuable references for the clinical application of titanium materials in chest wall reconstruction after the resection of metastatic BC.
The mass of simple and higher-order networks
Authors: Bianconi Ginestra
Published: November 2023

We propose a theoretical framework that explains how the mass of simple and higher-order networks emerges from their topology and geometry. We use the discrete topological Dirac operator to define an action for a massless self-interacting topological Dirac field inspired by the Nambu–Jona-Lasinio model. The mass of the network is strictly speaking the mass of this topological Dirac field defined on the network; it results from the chiral symmetry breaking of the model and satisfies a self-consistent gap equation. Interestingly, it is shown that the mass of a network depends on its spectral properties, topology, and geometry. Due to the breaking of the matter–antimatter symmetry observed for the harmonic modes of the discrete topological Dirac operator, two possible definitions of the network mass can be given. For both possible definitions, the mass of the network comes from a gap equation with the difference among the two definitions encoded in the value of the bare mass. Indeed, the bare mass can be determined either by the Betti number β
0 or by the Betti number β
1 of the network. We provide numerical results on the mass of different networks, including random graphs, scale-free, and real weighted collaboration networks. We also discuss the generalization of these results to higher-order networks, defining the mass of simplicial complexes. The observed dependence of the mass of the considered topological Dirac field with the topology and geometry of the network could lead to interesting physics in the scenario in which the considered Dirac field is coupled with a dynamical evolution of the underlying network structure.
CFD Simulation on the Effect of Adding Dimple Balls Stagger Position on Base Plate on the Performance of V-Corrugated Air Heating Solar Collector
Authors: Hakam Mohamad , Nugroho Priyambodo Nur Ardi , Habibah Ummi
Published: November 2023

The ever-increasing increase in energy consumption requires great attention. Therefore, efforts need to be made to find new energy sources, such as solar energy. The absorber plate absorbs solar energy in the form of radiation, and heat is transferred by convection to the working fluid through the solar collector. Increasing the thermal efficiency of the solar air collector by modifying the absorption area using a v-corrugated absorber and also increasing the convection heat transfer coefficient by creating turbulence in the heat transfer area. Flow turbulence can be achieved by providing a disturbance in the form of a dimple in the working fluid channel above the base plate. This research was conducted utilizing numerical simulations and experiments. CFD simulation aims to obtain the most optimum ratio of ΔT/ΔP values of diameter and dimple distance using ANSYS Fluent software with a diameter variation of 6mm, 8mm, 10mm, and 45mm spacing; 50mm, and 5mm. Based on the results of CFD simulations that have been carried out on each variation of the distance and diameter of the dimple, it can be concluded that the closer the distance between the dimples, the smaller the resulting pressure drop, and the larger the diameter of the dimple, the greater the resulting temperature value. The use of a larger dimple diameter results in an increase in the heat transfer area and further increases the outlet temperature. The expected ratio is the value of the largest temperature increase and the smallest pressure drop. In the calculation of the total ratio, the dimple diameter of 10 mm with a distance of 45 mm has the highest ΔT/ΔP ratio value.
Design and Fabrication of SNI Helmet on Free Fall Test Using the Ulrich Design Method
Authors: Hakam Mohamad , Afif Muhammad Nur , Bisono Fipka , Nugroho Priyambodo Nur Ardi , Ardliana Thina , Dhika Aditya P , Indrawan Rizal
Published: November 2023

SNI helmets have the highest assessment criteria in the digestive process regarding design, production, and market-to-target buyers. The design of this helmet emphasizes functionality rather than aesthetics. Careful planning must be done because it is the primary goal of this research, the theoretical basis of the fourth and fifth editions of the Ulrich method of product design development with score screening and concept selection using the product design style to be able to find complex case problems with great detail and reduce large production costs because of solving cases by maximizing the results of planning and designing the third concept with a score of 3.4 and a rate of 13 is the best, and the concept was chosen because it excels in the four selected aspects. Hence, proceed to the fabrication process. In the following score assessment, it is hoped that the parameters will be much more detailed to maximize the function and get closer to the details of the assessment so that it can be valid and objective.
Construction of Fishing Vessel Molding with A Case Study of Ship Objects for The Java South Sea Region
Authors: Karyono Tri , Setiawan Bambang Teguh , Herijono Boedi , Budianto
Published: November 2023

In the process of building fiberglass boats (FRP), mold or molding is needed to make the hull and superstructure. Molding can be made of several kinds of main constituent materials including steel, wood, aluminium, HDPE and others. The object of the case study was carried out by collecting data from existing ships at the South Coast of the Java Sea. Molding is the main means in the fabrication process for fiberglass boats. To find out how long the mold or molding can be used, a service life analysis is needed. In terms of current technology, the analysis method uses structural fatigue analysis or fatigue analysis. In the calculations, the design is carried out earlier by conducting modelling simulations. In the fatigue analysis of the molding structure, material data is required to be applied to the molding. This will provide input data at the preprocessing stage in the finite element method. Furthermore, if the lifetime results are known at the age of the mold, then it can be continued with making the fishing boat molding product. So that later it can provide an illustration for shipbuilders that the time or age of the mold can be used for the time that has been designed.
Harnessing Technology for Environmental Method: Cultivating High Order Thinking Skills for Sustainable Maritime Development Knowledge
Authors: Hanan Abdul , Marjani Gustiana Isya , Suherman Usep , Firdaus Ahmad , Albustomi Ahmad Gibson , Solehudin  , Goffary Irfan , Anwar Saeful , Mu’min  , Arken M. Rachmatullah
Published: November 2023

There The objective of this research is to identify effective strategies for leveraging technology to enhance the understanding of students and practitioners in the maritime sector regarding Higher Order Thinking Skills (HOTS). Furthermore, it aims to underscore the importance of designing relevant and up-to-date curricula while offering suitable learning platforms that align with technological advancements. Employing a quantitative approach, the study indicates that HOTS-based learning has an impact on increasing maritime awareness among students in Bandung city. This study illuminates’ phenomena in the realm of maritime education and the potential integration of technology in fostering High Order Thinking Skills (HOTS). The research findings highlight that the integration of HOTS represents an effective approach to enhance analytical capabilities, promote active involvement, enhance creative problem-solving abilities, and ultimately instill enduring environmental consciousness. These research findings provide a robust foundation for concluding that the implementation of Learning-based HOTS methods significantly enhances sustainable maritime knowledge and awareness.
Recovery of sugarcane bagasse as adsorbent for chromium (Cr) (III) removal
Authors: Apriani Mirna , Nindyapuspa Ayu , Cahyani Friska Dyah Ayu Febri , Nugraha Anggara Trisna
Published: November 2023

The aim of the study was to explore the ability of bioactivated carbon on Cr III removal. Chromium (III) is one of the heavy metals, toxic and harmful for human being causing spread pulmonary fibrosis disease. Adsorption is one of the alternatives and an effective purification and separation technique used in industrial wastewater treatment. Bioactivated carbon was obtained from sugarcane bagasse based agricultural biomass waste by furnace dried carried out at 400°C for 2h, activated by chemical using phosphoric acid. Bioactivated carbons were used to treat chromium (III) from artificial wastewater containing chromium. Cr (III) removal was investigated by the batch process with adsorbent dose, contact time and particle size to finding optimum conditions as an experiment variable. Bioactivated carbon resulting have surface area of 309.44 and 3133.82 m2/g, respectively for sizes 150 and 200 mesh using BET measurement. The predominance of carbon achieving 80.24%, 18.68% and 1.08% respectively for element C, O and Si, identified by SEM-EDX analyser. The optimum condition of the batch adsorption achieving 99.9% chromium removal, resulting from operation condition in 30 minutes contact time using 6 g adsorbent 200 mesh.
Effect of Graphite Addition on Thermal Behaviour of Metakaolin-Geopolymer Coating for Fire Protection of Steel
Authors: Putri Rena Yulia , Pratiwi Wiwik Dwi , Widiana Dika Rahayu , Aurora Tya Amalia Veridian , Auliyasari Inshiro
Published: November 2023

Geopolymers are inorganic binders that resulted from the alkali activation of aluminosilicate powder. Usually, geopolymers possess better high-temperature resistance than Portland cement-based materials. This makes them a promising candidate for high-temperature applications as well as for fire protection coating. The geopolymers pastes have been the focus as an intumescent coating. This study emphasizes the geopolymer pastes from metakaolin and silica fume precursors with the additive of graphite powder and intumescent compounds. The coupons test was made of carbon steel plate 50mm x 50mm x 4mm. Since steel loses a major of its mechanical properties at 500°C, then the time-temperature curve for the coated-steel plates was created from fire testing, compared to the naked steel. Moreover, the visual appearance and the SEM structure were recorded. It is found that the addition of graphite to geopolymer improves the fire resistance of geopolymer but does not affect the intumescent behaviour. is found that the geopolymer paste graphite addition did not result in better fire resistance.
Community Skill Development for the Use of Galvalume Composite Concrete Materials for Building Structural Parts
Authors: Mudjanarko Sri Wiwoho , Julianto Eko , Indartono Arie , Basuki Rahmat M. , Putu Artaya I , Rasidi Nawir , bahaswan Rizal , Harmanto Dani , Wiwoho Firdaus Pratama
Published: November 2023

Galvalume material is often known as Cold Formed Steel material. Galvalume is one component that is often used by the people of Indonesia as a building structure material. Galvalume is easy to use, easily available in the market, and relatively inexpensive. Mild steel profiles can be used instead of roof trusses made of wood and concrete. The problem so far is that innovation regarding the use of Galvalume material has not been widely used for building structures without being wrapped in concrete. In this study, a trial was conducted and the introduction of the application of the use of Galvalume to building structural materials. The methodology is carried out using galvalume which is made as a composite concrete stiffener. Composite concrete testing is only at the concrete compressive strength test stage. The results of the concrete panel test show that the galvalume material can be used and the workers who work on it are not too difficult to do.
Learning From Field Testing Experiences for Developing Small Scale Tidal Current Energy Conversion System
Authors: Rasgianti  , Mukhtasor  , Rahmawati Shade , Erwandi  , Juniarto Sony , Nugraha Ariyana Dwiputra , Simaremare Arionmaro Asi , Sitanggang Ruly Bayu
Published: November 2023

Tidal current energy conversion system (TCECS) has been tested in potential straits such as the Larantuka Strait and Madura Strait. In its development, the technology will be improved by increasing its capacity to 100 kW. The new capacity is planned to use a farming system with vertical axis turbines. The experience of installing and operating a TCECS prototype with a capacity of 10-20 kW in Indonesia could be a valuable experience for the implementation phase of a TCECS with a higher capacity. This paper aims to report the experience of TCECS installation in Indonesia. According to previous installation experience, TCECS was made floating using a catamaran type as a supporting structure. This was done to facilitate the transportation process from the production site to the installation site. TCECS production was carried out in an area that is quite far from the installation area because there is not enough land around it to assemble or produce the technology. This condition is one of the factors that need to be considered in the TCECS installation step in Indonesia. Another factor to consider is the size of the TCECS technology to be utilized. The Installation facilities in Indonesia, especially in the eastern region, have been yet inadequate in using large equipment, e.g., a heavy crane. Therefore, the dimensions of the TCECS to be installed should not have large dimensions. To take the experience of the installation, other factors are described in several chapters in this paper.
Analysis Adhesive Strength of Epoxy DGEBA on The Wooden Boat Hull
Authors: Imah Luluk K , Putu Arta Wibawa I , Gafur Abdul , Widodo Eriek W.R. , Dianita W , Tamimah Nimatut , Sumardiono  , Agung P.U , Abdullah Kharis , Dhiya Anissa U
Published: November 2023

Epoxy is a thermosetting material that is widely used as an adhesive. Epoxy has the advantages of good tensile strength, bending strength, and thermal stability. Epoxy is an adhesive that can bind various materials such as steel, copper, wood, iron, cement, plastic, and composites. Epoxy can be cured at room temperature with the addition of a hardener (curing agent). The curing agent affects the strength, hardness, durability, and adhesion strength of the epoxy. Along with the advancement of shipping technology, other alternatives were found in the construction of wooden ships, namely the laminate system. Wood lamination usually uses an epoxy resin material. Research on the strength of laminated materials for wooden hulls is an interesting scientific discussion to obtain new alternative materials that can be applied to wooden hulls. With this lamination method, it is very possible to replace wood because, with lamination, the material in addition to having better strength is also easy to obtain at a cheaper price than wood. Considering that this laminate material is still rarely used on ships, it is necessary to test the adhesive material. This research was conducted to see the mechanical characteristics and evaluate the use of laminated materials. The tests carried out included tensile test, and adhesive test which were carried out in the laboratory to obtain results to analyse the strength and durability of the wooden hull. The adhesive strength of DGEBA epoxy on teak wood has the highest adhesive strength on Epoxy-Amide with a paint coating of 4.43 MPa and tensile strength of 1.5 MPa. Meanwhile, the highest adhesive strength for Epoxy-Amine with paint coating is 4.76 MPa and tensile strength of 3.63 MPa which is applied to teak wood as a wooden ship hull material.
Assessment of hybrid MPPT for SPV based high gain cubic boost converter interfaced with reduced switch multilevel inverter for power quality enhancement
Authors: Veerabhadra J , Rao S Nagaraja
Published: November 2023

A high-gain cubic boost converter (HG-CBC) with hybrid-based maximum power point tracking (MPPT) through a neural network (NN) aided by the P&O technique (HNN-PO MPPT) has been suggested to acquire optimum power from a solar photovoltaic (SPV) model under varying climatic conditions. The SPV’s output is enhanced using the suggested HG-CBC as per the requirement. A detailed comparison of different conventional boost converters (BC) with the suggested HG-CBC is presented, mainly highlighting part count and boost factor (B). Using the MATLAB tool, the functionality of the developed HNN-PO MPPT technique has been examined for constant and different irradiation (G) levels. The hybrid-based MPPT helps quickly attain maximum power point (MPP) with minimum oscillations at the output. The convergence period is very short with high precision in comparison with P&O and NN MPPT. The results are examined between the suggested and traditional MPPT methods in relation to the percentage of oscillations and rise time. The Reduced Switch Multilevel Inverter (RSMLI) is proposed to integrate the SPV with the RL load. The RSMLI is compared with the conventional standard five-level MLI in relation to the quantity of DC sources, diodes, switches, capacitors, and other parts utilized. The suggested MLI involves a reduced switch count, which mitigates the overall losses during switching and hence improves the efficiency of an inverter. MLI switches are controlled using a sine Pulse Width Modulation (PWM) technique. The THD of the output current of a five-level RSMLI is 4.47%, and it falls within the IEEE 519 norm. Hence, output power quality is enhanced.
An experimental and numerical study: to investigate the switching characteristics of a field-distortion sparkgap switch in various SF6 admixtures
Authors: Kumar G Vinod , Verma Rishi , Singh Gursharn , Warrier Manoj Kumar , Sharma Archana
Published: November 2023

Pressurized sparkgap switch is one of the major components that is most commonly used in various pulsed-power systems and the stochastic closure time delay (t

d
) and jitter (σ

d
) in this gas discharge switch has substantial effect on the temporal characteristics of output pulse. Experimental investigations performed with various volumetric concentrations of SF6 in SF6-N2, SF6-dry air and SF6-Ar admixtures evidenced that the intrinsic parameters of the switch such as time delay and jitter were found to be strongly dependent on the nature of gas, volumetric concentration of SF6 in admixture and rate of rise of voltage (dV/dT) of applied trigger pulse for e.g. in SF6/N2 admixture experiments as the concentration of SF6 was increased from 5% to 50% the average time delay and jitter was consequently increased from 278 ns to 413 ns and 17 ns to 56 ns, respectively. The similar increasing trend was observed even in SF6/dry air and SF6/Ar admixture experiments. It was also observed in the investigation that the variation in time delay and jitter is relatively much lesser for the condition when fast rising trigger pulse having slew rates ∼500 V ns−1 is applied than that of trigger pulse with lower dV/dT of ∼3 V ns−1. To further corroborate the stochasticity of streamer discharge in experimented SF6 admixtures, numerical studies have also been carried out by using a Particle-In-Cell/Monte Carlo Collision (PIC/MCC) model. Our experimental and simulation results infer that SF6/Ar admixture with low SF6 concentration is a superior alternative than pure SF6 for pulsed power switching applications.
Application of kernel principal component analysis for optical vector atomic magnetometry
Authors: McKelvy James A , Novikova Irina , Mikhailov Eugeniy E , Maldonado Mario A , Fan Isaac , Li Yang , Wang Ying-Ju , Kitching John , Matsko Andrey B
Published: November 2023

Vector atomic magnetometers that incorporate electromagnetically induced transparency (EIT) allow for precision measurements of magnetic fields that are sensitive to the directionality of the observed field by virtue of fundamental physics. However, a practical methodology of accurately recovering the longitudinal angle of the local field through observations of EIT spectra has not been established. In this work, we address this problem of angle determination with an unsupervised machine learning algorithm utilizing nonlinear dimensionality reduction. The proposed algorithm was developed to interface with spectroscopic measurements from an EIT-based atomic rubidium magnetometer and uses kernel principal component analysis (KPCA) as an unsupervised feature extraction tool. The resulting KPCA features allow each EIT spectrum measurement to be represented by a single coordinate in a new reduced dimensional feature space, thereby streamlining the process of angle determination. A supervised support vector regression (SVR) machine was implemented to model the resulting relationship between the KPCA projections and field direction. If the magnetometer is configured so that the azimuthal angle of the field is defined with a polarization lock, the KPCA-SVR algorithm is capable of predicting the longitudinal angle of the local magnetic field within 1 degree of accuracy and the magnitude of the absolute field with a resolution of 70 nT. The combined scalar and angular sensitivity of this method make the KPCA-enabled EIT magnetometer competitive with conventional vector magnetometry methods. © 2023. All rights reserved.
Selective fluoride ion sensing in aqueous medium using ultrathin film of functionalized single-walled carbon nanotubes
Authors: Taneja Parul , Manjuladevi V , Gupta R K , Gupta K K
Published: November 2023

The presence of fluoride ion (F
-
) in potable water above its permissible limit (1–4 ppm) poses serious health hazards. Hence, detection of fluoride in potable water is essential. The π-electron rich single-walled carbon nanotubes can interact with F- to form semi-covalent C-F bond which can act as a basis for F
-
sensing in aqueous medium. Here, a single layer of octadecylamine functionalized single-walled carbon nanotubes (ODA-SWCNTs) was transferred onto solid substrates by the Langmuir–Schaefer (LS) method and employed for sensing of F- in aqueous medium by recording piezo and electrochemical responses, simultaneously using an electrochemical quartz crystal microbalance. The lowest detectable concentration and range of detectable concentration of fluoride ion were found to be 0.5 ppm and 0.5–145 ppm, respectively. The analysis of the LS film of ODA-SWCNTs before and after interaction with fluoride ion by Raman spectroscopy and grazing angle x-ray diffraction measurement reveals perturbation of π-electrons of the SWCNTs due to semi-covalent binding of the fluoride with the carbon atom of the nanotubes. The sensor showed a good selectivity towards the F- in the presence of some heavy metal ions. Testing of the sensor towards F- in tap water obtained from some local region showed a good accuracy.
Serum biomarkers and disease progression in CT-negative mild traumatic brain injury
Authors: Jia Xiaoyan , Li Xuan , Ji Qiuyu , Yin Bo , Pan Yizhen , Zhao Wenpu , Zhang Ming , Bai Guanghui , Zhang Jie , Bai Lijun
Published: November 2023

Blood proteins are emerging as potential biomarkers for mild traumatic brain injury (mTBI). Molecular pathology of mTBI underscores the critical roles of neuronal injury, neuroinflammation, and vascular health in disease progression. However, the temporal profile of blood biomarkers associated with the aforementioned molecular pathology after CT-negative mTBI, their diagnostic and prognostic potential, and their utility in monitoring white matter integrity and progressive brain atrophy remain unclear. Thus, we investigated serum biomarkers and neuroimaging in a longitudinal cohort, including 103 CT-negative mTBI patients and 66 matched healthy controls (HCs). Angiogenic biomarker vascular endothelial growth factor (VEGF) exhibited the highest area under the curve of 0.88 in identifying patients from HCs. Inflammatory biomarker interleukin-1β and neuronal cell body injury biomarker ubiquitin carboxyl-terminal hydrolase L1 were elevated in acute-stage patients and associated with deterioration of cognitive function from acute-stage to 6–12 mo post-injury period. Notably, axonal injury biomarker neurofilament light (NfL) was elevated in acute-stage patients, with higher levels associated with impaired white matter integrity in acute-stage and progressive gray and white matter atrophy from 3- to 6–12 mo post-injury period. Collectively, our findings emphasized the potential clinical value of serum biomarkers, particularly NfL and VEGF, in diagnosing mTBI and monitoring disease progression.
Where do we stand on fMRI in awake mice?
Authors: Mandino Francesca , Vujic Stella , Grandjean Joanes , Lake Evelyn M R
Published: November 2023

Imaging awake animals is quickly gaining traction in neuroscience as it offers a means to eliminate the confounding effects of anesthesia, difficulties of inter-species translation (when humans are typically imaged while awake), and the inability to investigate the full range of brain and behavioral states in unconscious animals. In this systematic review, we focus on the development of awake mouse blood oxygen level dependent functional magnetic resonance imaging (fMRI). Mice are widely used in research due to their fast-breeding cycle, genetic malleability, and low cost. Functional MRI yields whole-brain coverage and can be performed on both humans and animal models making it an ideal modality for comparing study findings across species. We provide an analysis of 30 articles (years 2011–2022) identified through a systematic literature search. Our conclusions include that head-posts are favorable, acclimation training for 10–14 d is likely ample under certain conditions, stress has been poorly characterized, and more standardization is needed to accelerate progress. For context, an overview of awake rat fMRI studies is also included. We make recommendations that will benefit a wide range of neuroscience applications.
The temporal dimension of parental employment: Temporary contracts, non-standard work schedules, and children’s education in Germany
Authors: Betthäuser Bastian A , Trinh Nhat An , Fasang Anette Eva
Published: November 2023

The increasing prevalence of non-standard work and its adverse consequences are well documented. However, we still know little about how common non-standard work is amongst parents, and whether its negative consequences are further transmitted to their children. Using data from the German Microcensus, we document the prevalence and concentration of temporary employment and non-standard work schedules in households with children in Germany. Second, we examine the extent to which variation in this temporal dimension of parental employment is associated with children’s school track. Results show that in about half of all German households with children in lower-secondary school at least one parent has a temporary contract or regularly works evenings or Saturdays. We find that children whose mother always works evenings or Saturdays are substantially less likely to transition to the academic school track. By contrast, we find no significant association between fathers’ non-standard work schedules and children’s school track. We also find no evidence of an association between parents’ temporary employment and children’s school track placement. These divergent findings highlight the importance of disaggregating non-standard work into its specific components and differentiating between mothers' and fathers' non-standard work when investigating the consequences of parental non-standard work for children’s educational and life chances.