Conventional Processing Technologies Research Articles

Toolpath generation in sub-regional processing with constraint of constant scallop-height at boundary for complex curved surface

Complex curved surface parts are widely applied in the manufacturing industry for specific functions. With the continuous improvement of the geometric complexity and the machining requirement, the conventional processing technology with uniform processing parameters is no longer applicable for this kind of parts, and the sub-regional processing with variable parameters is proposed. However, the obvious machined trace at the boundary between sub-regions appears easily in this way, which restricts the processing quality of complex curved surface parts seriously. To reduce the machined trace and realize the precise toolpath stitching, a toolpath generation method in sub-regional processing with constraint of constant scallop-height at boundary for complex curved surface is proposed. Firstly, the formation mechanism of the machined trace at the boundary between sub-regions is analyzed. Taking into account the geometric feature of the curved surface, the calculation model for the distance between boundary and cutter contact (CC) point is built. With constraint of constant scallop-height, the critical curve of CC points for the boundary between sub-regions is constructed. Then, the geodesics for the critical curve of CC points are calculated in side-step direction with a numerical method. The theoretical CC points on the geodesics are generated according to the estimated scallop-height and modified by the sensitivity analysis. Finally, the toolpaths are generated by connecting the theoretical CC points orderly and the actual CC points are determined in feed direction. A comparison experiment is carried out to verify the feasibility of the proposed toolpath generation method. The experimental results show that with the proposed method, the maximum of the profile deviation and the profile arithmetic average error at the boundary between sub-regions are 9.0 μm and 2.3885 μm respectively, which decrease by 74.43% and 34.98% compared with the results for the iso-level method. This research proves that the proposed toolpath generation method can realize the precise toolpath stitching and improve the processing quality in sub-regional processing, which provides guidance for the precision machining of the complex curved surface parts.

Peeling of kiwifruit using infrared heating technology: A feasibility and optimization study

Infrared (IR) technology has been studied as an alternative to conventional food processing technologies. The IR technology has attractive merits such as uniform heating, high heat transfer rate, reduced water, and energy consumption and improved product quality and safety. This research studied the feasibility of kiwifruit peeling using IR heating. The response surface methodology (RSM) was used to investigate the effects of IR radiation power (250–850 W), the distance between IR emitter and sample (10–70 mm) and heating time (45–125 s) on the peeling performance and physicochemical properties of kiwifruit. Lye-peeling was used as the control treatment to compare the efficiency of IR peeling. Heating with a power of 446 W at the distance of 70 mm for 125 s was found to be the optimum operating conditions for the IR peeling of kiwifruit. Under these conditions, the results were a peelability of 90%, weight loss of 4.5%, peel thickness of 0.4 mm, surface temperature of 64.1 °C, puncture force of 57.7 N, color difference of 2.4 and ascorbic acid content of 140 mg/100 g fresh fruit. Compared to hot lye peeling, the IR radiation heating caused significant reduction in weight loss, surface temperature, and color differences. It also maintained the firmness of fruits.

Environmental Aspects of Storing Tails of Ore Dressing in a Mountain Region

The tools for improving the environment state of mining regions is the optimization of mining and technological processes based on an assessment of the state of the natural environment when the technogenic load changes. The mining industry forms tailings storages for the processing of ores, which, in specific mountain conditions, determine the level of environmental impact. Conventional ore processing technologies do not ensure the extraction of metals from tailings of beneficiation to a level that allows them to be used in the national economy. Modernization of beneficating processes is possible using new leaching technologies, for example, processing in disintegrators. The ecological efficiency of waste-free utilization of tailings of beneficiation is achieved with system management of a set of extraction and processing processes taking into account the damage from environmental chemization. The efficiency of utilization of tailings of processing consists of reducing damage from the storage of tailings, the cost of commodity products obtained during processing, as well as reducing the technogenic load on the environment.

In situ atomic-scale observation of monolayer graphene growth from SiC

Because of its high compatibility with conventional microfabrication processing technology, epitaxial graphene (EG) grown on SiC shows exceptional promise for graphene-based electronics. However, to date, a detailed understanding of the transformation from three-layer SiC to monolayer graphene is still lacking. Here, we demonstrate the direct atomic-scale observation of EG growth on a SiC (1100) surface at 1,000 °C by in situ transmission electron microscopy in combination with ab initio molecular dynamics (AIMD) simulations. Our detailed analysis of the growth dynamics of monolayer graphene reveals that three SiC (1100) layers decompose successively to form one graphene layer. Sublimation of the first layer causes the formation of carbon clusters containing short chains and hexagonal rings, which can be considered as the nuclei for graphene growth. Decomposition of the second layer results in the appearance of new chains connecting to the as-formed clusters and the formation of a network with large pores. Finally, the carbon atoms released from the third layer lead to the disappearance of the chains and large pores in the network, resulting in a whole graphene layer. Our study presents a clear picture of the epitaxial growth of the monolayer graphene from SiC and provides valuable information forfuture developments in SiC-derived EG technology.

Special Issue on Wastewater Treatment and Reuse Technologies

Wastewater treatment allows for the safe disposal of municipal and industrial wastewater to protect public health and the ecosystem[...]

Nanoscale patterning of electronic devices at the amorphous LaAlO3/SrTiO3 oxide interface using an electron sensitive polymer mask

A simple approach is presented for designing complex oxide mesoscopic electronic devices based on the conducting interfaces of room temperature grown LaAlO3/SrTiO3 heterostructures. The technique is based entirely on methods known from conventional semiconductor processing technology, and we demonstrate a lateral resolution of ∼100 nm. We study the low temperature transport properties of nanoscale wires and demonstrate the feasibility of the technique for defining in-plane gates allowing local control of the electrostatic environment in mesoscopic devices.

In-Mapper combiner based MapReduce algorithm for processing of big climate data

Big data refers to a collection of massive volume of data that cannot be processed by conventional data processing tools and technologies. In recent years, the data production sources are enlarged noticeably, such as high-end streaming devices, wireless sensor networks, satellite, wearable Internet of Things (IoT) devices. These data generation sources generate a massive volume of data in a continuous manner. The large volume of climate data is collected from the IoT weather sensor devices and NCEP. In this paper, the big data processing framework is proposed to integrate climate and health data and to find the correlation between the climate parameters and incidence of dengue. This framework is demonstrated with the help of MapReduce programming model, Hive, HBase and ArcGIS in a Hadoop Distributed File System (HDFS) environment. The following weather parameters such as minimum temperature, maximum temperature, wind, precipitation, solar and relative humidity are collected for the study are Tamil Nadu with the help of IoT weather sensor devices and NCEP. Proposed framework focuses only on climate data for 32 districts of Tamil Nadu where each district contains 1,57,680 rows and so there are 50,45,760 rows in total. Batch view precomputation for the monthly mean of various climate parameters would require 50,45,760 rows. Hence, this would create more latency in query processing. In order to overcome this issue, batch views can precompute for a smaller number of records and involve more computation to be done at query time. The In-Mapper based MapReduce framework is used to compute the monthly mean of climate parameter for each latitude and longitude. The experimental results prove the effectiveness of the response time for the In-Mapper based combiner algorithm is less when compared with the existing MapReduce algorithm.

An atomic-scale and high efficiency finishing method of zirconia ceramics by using magnetorheological finishing

Zirconia ceramics is a valuable crucial material for fabricating functional components applied in aerospace, biology, precision machinery, military industry and other fields. However, the properties of its high brittleness and high hardness could seriously reduce its finishing efficiency and surface quality by conventional processing technology. In this work, we present a high efficiency and high-quality finishing process by using magnetorheological finishing (MRF), which employs the permanent magnetic yoke with straight air gap as excitation unit. The sub-nanoscale surface roughness and damage free surface can be obtained after magnetorheological finishing. The XRD results and SEM morphologies confirmed that the mechanical shear removal with ductile modes are the dominant material removal mechanism for the magnetorheological finishing of zirconia ceramic. With the developed experimental apparatus, the effects of workpiece speed, trough speed and work gap on material removal rate and surface roughness were systematically investigated. Zirconia ceramics finished to ultra-smooth surface with surface roughness less than Ra 1 nm was repeatedly achieved during the parametric experiments. Additionally, the highest material removal rate exceeded 1 mg/min when using diamond as an abrasive particle. Magnetorheological finishing promises to be an adaptable and efficient method for zirconia ceramics finishing.

The Impact of Nonthermal Technologies on the Microbiological Quality of Juices: A Review.

Fruit and vegetable juices are rich sources of nutrients that support microbiological growth and ultimately undergo rapid deterioration of safety and quality. The loss of nutritional quality of juices due to intensive thermal processing is a major problem encountered during the treatment of commercially preserved liquid foods. Conventional thermal processing technologies inactivate microorganisms and enzymes and extend the shelf life of foods but exert negative effects on nutritional and organoleptic properties of juices, for example, a loss of vitamins, of a desirable flavor, and of bioactive compounds and development of different sensory profiles as a result of heating. Nonthermal technologies including ultrasonication, a pulsed electric field, high-pressure processing, irradiation, and their combinations are suitable alternatives for achieving the same preservation effect without the adverse effects of heat on the quality of juices and meet consumer demand for clean-label, safe, and wholesome products without compromising their nutritional properties.

Investigating consumers' perception of apple juice as affected by novel and conventional processing technologies

SummaryThis work evaluates consumers' perception of apple juice processed by high pressure processing (HPP) and pulsed electric field (PEF) compared with thermal processing. As a case study, young Chinese immigrants living in New Zealand were selected. Targeting a broad understanding of process impact, three industrially relevant apple cultivars (New Zealand Jazz, Rose and Granny Smith) were chosen. The consumer study was performed using napping with ultra‐flash profiling technique (n = 38). The process impact on sensory perception seems to vary among the investigated apple cultivars. For Jazz and Granny Smith apple cultivars, PEF‐ and HPP‐treated juices are perceived as fresh, natural, sweet and balanced flavour. For Rose apple cultivar, however PEF‐processed juices appear to be perceived as fresh flavour in comparison with HPP and thermally treated juices. Moreover, thermal processing caused cooked flavour. With respect to colour, immediately after processing, HPP retains the natural apple juice colour compared with other treatments.

Protective molecular passivation of black phosphorus

Black phosphorus is a fascinating layered material, with extraordinary anisotropic mechanical, optical and electronic properties. However, the sensitivity of black phosphorus to oxygen and moisture poses significant challenges for technological applications of this unique material. Here, we report a viable solution that overcomes degradation of few-layer black phosphorus by passivating the surface with self-assembled monolayers of octadecyltrichlorosilane that provide long-term stability in ambient conditions. Importantly, we show that this treatment does not cause any undesired carrier doping of the bulk channel material, thanks to the emergent hierarchical interface structure. Our approach is compatible with conventional electronic materials processing technologies thus providing an immediate route toward practical applications in black phosphorus devices.

Three-dimensional graphene nanosheets supported by NiO/Si-MCP as electrode materials for high-performance supercapacitors

A three-dimensional (3D) graphene/NiO/Si-microchannel (MCP) composite electrode is synthesized by the conventional microelectronic machining process and electrochemical exfoliation technology for electrochemical capacitors. SEM, AFM, and Raman scattering are used to investigate the morphology and structure, and electrochemical characterization reveals that the 3D graphene/NiO/Si-MCP has a high specific capacitance of 833 Fg−1 at a current density of 5 Ag−1 in 6 mol L−1 KOH. Moreover, good cycling performance with 92% capacitance retention after 1000 cycles is observed indicating the novel electrode has large potential in high-performance supercapacitors.

Hydrogen applications and research activities in its production routes through catalytic hydrocarbon conversion

Abstract The statistical information on the share of hydrogen sector-wise consumption indicates that 95% of the total consumption is utilized in ammonia synthesis, petroleum refining processes and methanol production. We discuss how hydrogen is used in these processes and in several smaller-scale manufacturing industries. We also present the trend of hydrogen used as fuel, and as an energy carrier in fuel cells for generating electricity, powering hydrogen vehicles, as well as in aerospace applications. Natural gas caters for approximately half of the total hydrogen production resources. Therefore, the scope is emphasized on relatively recent developments in research activities related to the conventional catalytic hydrocarbon processing technologies for the production of hydrogen derived from natural gas (methane), which are steam methane reforming, partial oxidation of methane and autothermal reforming. Hydrocarbon decomposition is included due to its potential to be industrialized in the future, and its benefits of producing clean hydrogen without emissions of greenhouse gases and generating carbon nanofibers or nanotubes as by-products that have the potential in various emerging applications. Attention is given to the efforts toward achieving hydrocarbon conversion improvements, energy savings through thermally efficient operation and reduced operational costs through minimization or elimination of coke formation in the catalytic processes.

On‐chip laser processing for the development of multifunctional microfluidic chips

AbstractIn the development of microfluidic chips, conventional 2D processing technologies contribute to the manufacturing of basic microchannel networks. Nevertheless, in the pursuit of versatile microfluidic chips, flexible integration of multifunctional components within a tiny chip is still challenging because a chip containing micro‐channels is a non‐flat substrate. Recently, on‐chip laser processing (OCLP) technology has emerged as an appealing alternative to achieve chip functionalization through in situ fabrication of 3D microstructures. Here, the recent development of OCLP‐enabled multifunctional microfluidic chips, including several accessible photochemical/photophysical schemes, and photosensitive materials permiting OCLP, is reviewed. To demonstrate the capability of OCLP technology, a series of typical micro‐components fabricated using OCLP are introduced. The prospects and current challenges of this field are discussed. image

A study on micro hydroforming using shock wave of 355 nm UV-pulsed laser

In this paper, we proposed a new manufacturing technology of micro hydroforming using 355nm ultraviolet(UV)-pulsed laser. Hydroforming is known as a well-established technology to manufacture metallic parts, in particular for mass production of sheet metal, for several industrial applications such as automobiles, battery and military products. In addition laser shock processing(LSP) has been developed as the expanded applications of electrical and mechatronic devices. When the material was exposed to laser beam, multiple phenomena like the photochemical, the photothermal and the photomechanical effect are simultaneously occurred at the spot area. Especially, the photothermal effect due to laser heat transfer makes it hard to improve the accuracy of laser processing. To reduce the thermal effect and to enhance the photomechanical effect, the laser was irradiated under water in this paper. Strong forming pressure of LSP was provided by the higher density of water than air, which could help directly manufacture the thin sheet metal materials like as laser direct writing. We also conducted computer simulation using finite element method(FEM) to demonstrate its deformation behaviour with and without the strain rate effect of 104–105 (sec−1). Compared with conventional processing technology, this new method can provide high selectivity, excellent hydroforming efficiency and lower cost to achieve micro grooving pattern on the surface of thin metal sheet.

Compression testing of martensitic stainless steel with superimposed ultrasonic vibration

Abstract The expanding use of materials with high strength in cold forging and the associated force increases as well as the limited formability present a major challenge for conventional process technology. One method to respond to this challenge is the use of high frequently oscillating forming tools which lead to a decrease of the required forces. Previous research on this topic has focused on fairly soft materials, such as aluminum. Materials with higher strength have only been analyzed to a very limited extent. This study addresses the ultrasonic-assisted compression testing of high strength martensitic stainless steel with 20 kHz oscillation frequency aiming at the identification of relevant process parameters and the partial separation of occurring effects. Experimental investigations are carried out to analyze the effect of ultrasonic-assistance during compression testing with varying oscillation duration and amplitude on the maximum forming force and on specimen heating. To isolate the proportional force reduction due to material heating from other oscillation induced causes, a comparison with conventional warm compression tests is performed. Finally, a simplified numerical simulation which is able to model the ultrasonic-assisted compression test is proposed. The experimental results reveal a strong influence of the oscillation amplitude on the reduction of maximum forces and on specimen heating. The oscillation duration presents a minor influence on the maximum forces, but strongly affects the heat generation. The developed simulation model is in good accordance with experimental force displacement curves and allows the separation between stress superposition and other ultrasonic-induced effects.

Innovative Alternative Technologies to Extract Carotenoids from Microalgae and Seaweeds.

Marine microalgae and seaweeds (microalgae) represent a sustainable source of various bioactive natural carotenoids, including β-carotene, lutein, astaxanthin, zeaxanthin, violaxanthin and fucoxanthin. Recently, the large-scale production of carotenoids from algal sources has gained significant interest with respect to commercial and industrial applications for health, nutrition, and cosmetic applications. Although conventional processing technologies, based on solvent extraction, offer a simple approach to isolating carotenoids, they suffer several, inherent limitations, including low efficiency (extraction yield), selectivity (purity), high solvent consumption, and long treatment times, which have led to advancements in the search for innovative extraction technologies. This comprehensive review summarizes the recent trends in the extraction of carotenoids from microalgae and seaweeds through the assistance of different innovative techniques, such as pulsed electric fields, liquid pressurization, supercritical fluids, subcritical fluids, microwaves, ultrasounds, and high-pressure homogenization. In particular, the review critically analyzes technologies, characteristics, advantages, and shortcomings of the different innovative processes, highlighting the differences in terms of yield, selectivity, and economic and environmental sustainability.

Using Forest Resources to Develop High Performance Plastic Compounds for the Automotive Industry

AbstractThis study explores new applications for wood fibres through their incorporation on plastic matrices, developing high performance compounds for the automotive interior. Different automotive grades of polypropylene were reinforced with pine and eucalyptus fibres, in order to compare their properties with the specifications of different vehicle parts. The composites were produced using conventional plastics processing technologies, namely compounding with twin-screw extruder and injection molding. Mechanical properties, density, heat deflection temperature and Vicat softening point were determined. Other specific tests were carried to understand the feasibility of these composites use in automotive parts, namely fogging and flammability and also the determination of the tensile properties after climatic aging tests. The fibres morphology and its distribution and dispersion in the polymer matrices were evaluated by optical and scanning electron microscopy. The results show that it is possible to reinforce the raw-materials using wood and achieve the high standards of the automotive industry, producing environmentally friendlier materials, through the effective reduction of the use of plastic. This work enabled important conclusions regarding the incorporation of wood into PP matrices without compromising the specifications of certain dashboard parts and it also allowed evaluating the processability of these composites.

Controllable Hysteresis and Threshold Voltage of Single-Walled Carbon Nano-tube Transistors with Ferroelectric Polymer Top-Gate Insulators.

Double-gated field effect transistors have been fabricated using the SWCNT networks as channel layer and the organic ferroelectric P(VDF-TrFE) film spin-coated as top gate insulators. Standard photolithography process has been adopted to achieve the patterning of organic P(VDF-TrFE) films and top-gate electrodes, which is compatible with conventional CMOS process technology. An effective way for modulating the threshold voltage in the channel of P(VDF-TrFE) top-gate transistors under polarization has been reported. The introduction of functional P(VDF-TrFE) gate dielectric also provides us an alternative method to suppress the initial hysteresis of SWCNT networks and obtain a controllable ferroelectric hysteresis behavior. Applied bottom gate voltage has been found to be another effective way to highly control the threshold voltage of the networked SWCNTs based FETs by electrostatic doping effect.

A systematic approach to recycling organics for horticulture: comparing emerging and conventional technologies

Recycled organics: how best to use this resource? A three-year study took the first steps towards an answer by exploring emerging (biochar from pyrolysis) versus conventional (composting) processing technologies for their ability to convert recycled organics-city green waste and farm trash-into usable products that enhance horticultural productivity, with attendant carbon sequestration and environmental benefits. In this study, we compared organic products prepared from one common feedstock using four different technologies: windrow composting; a small mobile pyrolyser for on-farm processing; a medium pyrolyser for community or small business undertakings; and a large pyrolyser for high through-put requirements. The project then determined whether organic products enhance plant performance, are useable for horticulture and outperform or complement composting. This paper summarises some key outcomes from i) physical and chemical characterisation of organic products and ii) annual vegetable (tomato 'Rebel') and perennial fruit (blueberry 'Opi') field trials, thus providing the first step towards an understanding of the system from feedstock source to the farm.