machinery
Not a member yet
8395 research outputs found
Sort by
Thermal decomposition of spent lithium-ion batteries pouch: Investigating kinetic and thermodynamic compensation effects
No full textA deeper understanding of the pyrolysis process for main and additional components in spent lithium-ion batteries (LIBs) could provide valuable insights for optimizing their recycling processes. This study examined the thermal behavior, kinetics, thermodynamics, and product evolution during the pyrolysis of laminate pouch primarily composed of polypropylene and polyamide. The kinetic compensation effect (KCE) and thermodynamic compensation effect (TCE) were also probed to provide a comprehensive understanding of the conversion. The degradation process was divided into three stages, with total mass loss ranging from 31.14 to 40.28 % and peak temperatures between 419 and 472 °C. The average activation energy was determined to be 118.06 kJ mol−1, with specific values of 99.25, 119.06 and 139.31 kJ mol−1 within conversion rate of 0.10–0.30, 0.35–0.75 and 0.80–0.95, respectively. The pouch conversion followed D1 diffusion mechanism. The KCE was confirmed and reconstructed
displayed an excellent fit. Thermodynamic analysis implied that this conversion process was endothermic and non-spontaneous. Enthalpy and entropy relationship demonstrated the existence of TEC with compensation temperature (Tcomp) and experimental temperature (Texp) of 676.20 K and 693.23 K, respectively. In addition, free energy of compensation (ΔGcomp) was found to be 164.51 kJ mol−1, in agreement with experimental binding free energy (ΔGexp) range of 166.48–170.65 kJ mol−1, further confirmed the validity of the adopted mechanism
Unsteady Fluid-Structure Interaction Characteristics of a Reversible Mixed-Flow Pump in Micro-Pumped Hydro Storage
No full textThe reversible mixed-flow pump (RMFP) is widely employed in micro-pumped hydro storage to efficiently meet the energy storage and generation demands of microgrids. However, frequent switching between operational conditions intensifies the fluid–structure interaction effects
in RMFP, leading to operational instability and blade fatigue damage. In this paper, the unsteady flow and dynamic characteristics of RMFP in pump and turbine modes are systematically investigated through numerical simulation and experimental verification. Comprehensive
comparative analysis was conducted on the pressure distribution, radial force, as well as the deformation and stress distribution at different locations of the impeller blades under various operational conditions in both pump and turbine modes. The results show that: In pump
mode, the pressure distribution on the blade’s pressure side is uniform, while in turbine mode, a localized high-pressure region forms at the inlet under high head condition (9 m). Significant fluctuations in radial force are observed under low flow rate pump condition (0.8Qd). The
maximum deformation of the impeller is 0.1236mm in pump mode under low flow rate condition (0.8Qd) and 0.184mm in turbine mode under high head condition (9 m). Equivalent stress concentrations predominantly are observed at the blade inlet in turbine mode and the
blade outlet in pump mode, with significant stress accumulation at the hub-bearing connection. These findings provide valuable insights for the operational stability of the RMFP rotor system and offer guidance for the structural optimization of impeller blades
History of Bucket Wheel Excavators: From the First Construction to the Guinness World Record for the Heaviest Land-Based Vehicle Ever Built
No full textA bucket-wheel excavator (BWE) is a large heavy equipment machine used in surface mining. The history of heavy equipment and excavators reaches even earlier times. Earth-moving tools and bucket wheels go back to ancient times, while the first known excavator design came in around 1420. Before the use of BWE, the first documented use of a bucket chain excavator was in 1859 by Alphonse Couvreux, a French entrepreneur. This paper presents some notes on the history of BWEs, starting from the first construction of the rail-mounted BWE, which was first put into operation in 1916, in the surface mine Bergwitz in Germany to the Guinness World Record for the heaviest land-based vehicle ever built: The gigantic Bagger 293 weighting 14,200 tones, a BWE built in 1995 used for strip-mining operations. This heaviest earthmoving machine, with the digging output of 240,000 m3 per day, is capable of moving under its own power. Historical development and evolution of BWEs led to the enormous increase of the output of those machines over the next years
Recycling or Sustainability: The Road of Electric Vehicles Toward Sustainable Economy via Blockchain
No full textThis semi-systematic review paper discusses four research questions based on findings from the last 10 years: What are the crucial issues in the ongoing debate on the development of the electric vehicle (EV) concept? Where are the major conflicting points and focuses between sustainable economy and EVs? How does the mining of metals and minerals follow current zero-waste sustainability trends, and how does the prediction of the magnitude of the future demand for EV batteries guide strategic decision-making in policies throughout the globe? As it is not easy to currently predict how metals necessary for EV productions will be produced, this article suggests a strategy that is diverse regarding its approaches to shaping the sustainable mining and further development of EVs, along with the involvement of urban planning. Using broad literature and a published pool of prediction scenarios, we provide a comprehensive assessment of future EV battery raw materials development under a range of scenarios, accounting for factors such as developments in battery technology, variations in the EV fleet composition, sustainability aspects of development of second use and recycling technologies. Additionally, this paper demonstrates how blockchain technology is likely to force mineral and metal supply chains to become significantly more traceable and transparent.Project no. 451-03-136/2025-03/2000
REQUIRED LIMITS FOR nZEB FOR DIFFERENT CATEGORIES OF BUILDINGS
No full textThe paper presents the critical discussion on different nZEB minimum energy performance requirements in EU countries and possibility of their application in the Republic of Serbia. EU countries set their limits for nZEB for new and existing buildings differently, and within their national frameworks. The Republic of Serbia hasn’t adopted new regulation based on revised EPBD from 2024. yet, but being on the EU road it is necessary to develop national regulations based on experiences of other countries. Based on the EPBD, it is necessary to define the minimum requirements for new buildings and develop renovation strategies for existing building stock for energy consumption reduction and mitigation of greenhouse gases effect. Some of the categories of buildings are very challenging and therefore it is very important to set the right minimum energy performance requirements within the national regulations. The analysis in this work was done for the renovation of existing multifamily residential building in the Republic of Serbia to the nZEB level. Possible energy efficiency measures are proposed for three different cases. The results showed that possible primary energy reduction after the implementation of a package of different energy efficiency measures was about 88%, while the possible CO2 emission reduction was about 83%. Properly set nZEB minimum energy performance requirements in future national regulations will lead to intensive energy consumption reduction and CO2 emission reduction as well, which will further lead to the fulfillment of EPBD goals and decarbonization of the building sector
FARADEJEV KAVEZ OD GRAFENA
No full textOvaj pronalazak se odnosi na Faradejev kavez izrađen od grafena. Grafen se koristi kao osnovni materijal zbog svoje visoke električne provodljivosti, mehaničke čvrstoće i fleksibilnosti. Faradejev kavez od grafena pruža efikasnu zaštitu od elektromagnetnih talasa, dok je znatno lakši i fleksibilniji od tradicionalnih metalnih kaveza. Grafen može biti korišćen u obliku jednog sloja ili više slojeva, a slojevi grafena odnosno ploče grafena koje naležu jedna na drugu celokupnom svojom površinom mogu biti spojene termički, elektrohemijski, laserski, ultrazvučno, polimerno ili na drugi pogodan način koji ne ugrožava čvrstoću kaveza i ne narušava električnu provodljivost kaveza. Grafenske ploče se mogu spajati po ivicama pomoću tehnika kovalentnog vezivanja, termičkog zavarivanja, provodljivog lepka, leksibilnih provodnih traka i na drugi pogodne načine kako bi se formirala kontinuirana stabilna i provodna struktura. Ovaj kavez se može koristiti u različitim industrijskim, medicinskim, telekomunikacionim, vojnim aplikacijama, kao i za zaštitu osoblja i opreme u rudarskim i istraživačkim okruženjima.Contract no. 451-03-47/2023-01/20010
Modelling and Simulation of an Electromagnetic Vibratory Actuator Using CAD Software
No full textThe paper presents a model of an electromagnetic actuator that is used as an excitation element of vibratory conveyors and feeders. Considering the nonlinearity of the electromagnetic actuator, it is important to investigate its model and perform certain simulations. The model was checked with the EMWorks simulation package. Key simulation results are presented at the end of the paper.IEEE Catalog Number: CFP25JAH-ART
ISBN 979-8-3315-1579-
Temperature Response, Time Delay, and Hysteresis Loop of Heat Loss Flowmeter Thermistors
No full textA heat loss flowmeter for water was made of two
negative temperature coefficient (NTC) thick film thermistors
Th1 and Th2 and placed in a metal housing. The first thermistor
Th1 is cold and measures input water temperature Tw,
and the second thermistor Th2 is self-heated at a constant
voltage and measures water flow rate Q. At first temperature
responses T(Q), heat loss and time delay td were
measured and analyzed; then a temperature hysteresis loops
of self-heating thermistor at switching waterflow regime
was measured. The electrical responses I(Q) were measured
using the flowmeter and digital acquisition card (DAC).
An independent ultrasonic flowmeter was used in series
with a novel heat loss flowmeter. The current values of
temperature T(Q, t) of the water flow Q(t) were obtained
using Steinhart–Hart equation for thermistors. Input water
temperature Tw was used as a parameter (in the range of 5 ◦C–25 ◦C). The maximum thermistor power dissipation
was less than 1 W. The inaccuracy of the water flow rate measurement was estimated to be less than 3%. The measuring
flowmeter range of 0.003–0.3 L/s (1/2 in pipe) is suitable for measuring water consumption in households
Modeling of fracture toughness size effect in ductile-to-brittle transition temperature region: features and demonstration
No full textThe significant scatter observed in experimental fracture toughness data, a characteristic feature of all ferritic steels within the ductile-to-brittle transition (DBT) temperature region, necessitated the incorporation of statistical methods for data processing. Owing to the inherent stochasticity of the fracture process, the application of fracture mechanics concepts in the characterization of the DBT phenomenon has remained a challenging endeavor over the past 50 years. Various models have been developed based on a statistical approach to data processing to capture the salient features of this phenomenon; however, all exhibit certain limitations due to the intrinsic complexity of the problem. Nevertheless, these models have provided a robust foundation for the continued development of novel approaches in the
characterization of DBT. This paper presents a comparative analysis of two such novel models.
These models incorporate size effects and utilize scaling of geometrically similar CT
specimens, aiming to predict fracture toughness. A common feature of both proposed models
by the authors in this study is the application of Weakest Link Statistics. Particularly, after the
presentation of both models methods, the EURO fracture toughness dataset for 22NiMoCr37
reactor steel is employed, and experimental data obtained at a temperature of -60 °C is
selected to demonstrate the accuracy of the estimates. The fracture toughness metric used is
the critical value of the stress intensity factor employed in the master curve (more precisely,
KJc). The obtained predictions show good agreement with the experimental results,
considering the inherent scatter nature of the experimental data. The presented methods are
mainly criticized regarding their application domain and their predictive capability for fracture
toughness. One important remark to emphasize is that the estimate of the KJc cumulative
distribution function, obtained by extrapolation using the novel two-step scaling method, is
sensitive to the statistical size of the input datasets
Dynamic data fusion analysis method for crack tracking in reinforced concrete based on DIC and AE
No full textMonitoring cracks within concrete structures allows for the assessment of performance and load-bearing capacity changes, enabling early preventative measures to enhance safety and durability. This paper addresses the challenges of using Acoustic Emission (AE) technology alone to monitor full-field strain changes at crack locations by implementing a dynamic data fusion method combining Digital Image Correlation (DIC) and AE technology. This method leverages the non-contact monitoring capabilities of DIC with the energy parameter analysis and circular trajectory localization of AE to achieve data fusion on the same specimen. The method is applied during four-point bending tests on reinforced concrete beams to track crack development at various stages. The results demonstrate significant improvements in the accuracy of concrete crack detection, precise tracking of crack evolution, and detailed data analysis of crack position and size at different stages of development. This provides effective experimental support and a theoretical basis for the health monitoring and safety assurance of reinforced concrete structures.Research, No. [451-03-65/2024-03/200105], dated February 5, 202