Mechanical Machine Research Articles

MP25-19 COMPARISON OF COMPLICATIONS, OPERATING TIME AND COSTS IN DOUBLE-LAYERED HAND-SEWN VS. MECHANICAL STAPLED ILEO-ILEAL ANASTOMOSIS DURING RADICAL CYSTECTOMY

You have accessJournal of UrologyCME1 May 2022MP25-19 COMPARISON OF COMPLICATIONS, OPERATING TIME AND COSTS IN DOUBLE-LAYERED HAND-SEWN VS. MECHANICAL STAPLED ILEO-ILEAL ANASTOMOSIS DURING RADICAL CYSTECTOMY Gabriele Tulone, Nicola Pavan, Sofia Giannone, Giuseppe Alario, Alberto Abrate, Mirko Pinelli, Piero Mannone, Francesco Claps, Davide Baiamonte, Rosa Giaimo, Marco Vella, Carlo Pavone, Vincenzo Ficarra, and Alchiede Simonato Gabriele TuloneGabriele Tulone More articles by this author , Nicola PavanNicola Pavan More articles by this author , Sofia GiannoneSofia Giannone More articles by this author , Giuseppe AlarioGiuseppe Alario More articles by this author , Alberto AbrateAlberto Abrate More articles by this author , Mirko PinelliMirko Pinelli More articles by this author , Piero MannonePiero Mannone More articles by this author , Francesco ClapsFrancesco Claps More articles by this author , Davide BaiamonteDavide Baiamonte More articles by this author , Rosa GiaimoRosa Giaimo More articles by this author , Marco VellaMarco Vella More articles by this author , Carlo PavoneCarlo Pavone More articles by this author , Vincenzo FicarraVincenzo Ficarra More articles by this author , and Alchiede SimonatoAlchiede Simonato More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002568.19AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The Intestinal anastomosis during radical cystectomy (RC), can be performed by hand suturing or by a mechanical suturing machine. The purpose of the study is to compare complications, timing and costs of the intestinal anastomosis techniques. METHODS: A multi-institutional cohort of 195 patients who underwent RC, performed by expert surgeons, from 2016 to 2021, were retrospectively analyzed. 100 (51.3%) double-layered hand-sewn intestinal anastomosis (HS-IA) with 2 Vicryl 3.0 and 2 Vicryl 4.0 stitches were performed. 95 (48.7%) mechanical stapled intestinal anastomosis (MS-IA) were conducted with a mechanical stapler (disposable Ethicon 75mm Linear Cutter from Johnson and Johnson) and 1 refill. RESULTS: Of the 195 procedures, 100 patients underwent HS-IA and 95 underwent MS-IA. The median age was 71 years (IQR 65-77 years). Charlson comorbidity index and ASA score were higher in the MS-IA group. 29 (29%) patients of the HS-IA group reported early postoperative complications and in 34 (36%) patients were documented in the MS-IA group (p<0.001). In the MS-IA group, 20 (21.1%) patients presented major complications according to Clavien Dindo, while only 6 patients (6%) had complications in the HS-IA group (p=0.03). In HS-IA group ileo-ileal anastomosis dehiscence occurred in 1 patient (1%); 1 patient (1%) had intestinal mechanical obstruction and 2 (2%) patients ileus in postoperative period. In the MS-IA group in 2 patients (2.1%) bowel perforation occurred, and intestinal obstruction in 2 patients was also reported. There is not a statistically difference in time to flatus and defecation, 2 days (IQR 2-3 days) vs 3 days (IQR 2-3 days) and 5 days (4-6 days) vs 5 days (4-6 days) respectively in the two groups. The median operating time for the hand-sewn anastomosis was 16.4 min (range 15.0-17.4 min), compared to 20.0 min (range 20.0 -20.0 min) p<0.001 for the mechanical suturing machine. The costs of the double-layered hand-sewn for a single patient is 5 €, against 350.00 € for a disposable mechanical stapler and one refill. CONCLUSIONS: Both HS-IA and MS-IA are safe and feasible without postoperative course differences but the HS-IA is less expensive and can reduce the operating time of the ileo-ileal anastomosis during RC. Additionally, MS-IA is reinforced with supplementary stitches and despite this, the risk of anastomosis dehiscence is not completely cancelled. Concluding, the HS-IA anastomosis is an important cost-saving approach compared to the stapled alternative. Source of Funding: No © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e436 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Gabriele Tulone More articles by this author Nicola Pavan More articles by this author Sofia Giannone More articles by this author Giuseppe Alario More articles by this author Alberto Abrate More articles by this author Mirko Pinelli More articles by this author Piero Mannone More articles by this author Francesco Claps More articles by this author Davide Baiamonte More articles by this author Rosa Giaimo More articles by this author Marco Vella More articles by this author Carlo Pavone More articles by this author Vincenzo Ficarra More articles by this author Alchiede Simonato More articles by this author Expand All Advertisement PDF DownloadLoading ...

Stress relaxation behavior of left ventricular myocardium in mice

BackgroundMyocardial tissues are known to exhibit viscoelastic behavior, i.e., the myocardial wall stress is gradually decaying when stretched at a constant level, referred to as stress relaxation behavior. The study of this behavior becomes important in structural heart diseases, where both passive and active relaxation behaviors of the myocardium may alter. As myocardial tissues display a complex, 3D micro‐architecture, the anisotropy of stress relaxation remains understudied. Our objective in this study was to investigate the anisotropy of (passive) stress relaxation behavior of the left ventricular (LV) myocardium in healthy small animals.MethodsWe used biaxial stress relaxation tests in wild‐type murine specimens (n=2). Full‐thickness myocardium LV free wall (LVFW) specimens were isolated from the mouse hearts (Fig. 1a), with the slab edges being aligned with the longitudinal (apex‐to‐outflow‐tract), circumferential, and radial directions of the LV. The specimens were mounted in a biaxial mechanical testing machine along the circumferential and longitudinal directions. The specimens were stretched in three different loading protocols with circumferential‐to‐longitudinal strain ratios of 30:30, 15:30, and 30:15%. The samples were loaded to the peak strain at a rate of 0.01 s‐1 and held at this stretch for 10 minutes to allow the relaxation. The time‐varying stress was recorded. We used an exponential decay fit to estimate the stress relaxation time constants in both directions.ResultsStress relaxation time constants showed noticeable differences between multiple loading ratios with equibiaxial loading (30:30) having the largest relaxation time constant followed by the circumferential stress in the 30:15 ratio (Fig. 1b). The larger strains led to larger stress relaxation constants (Fig. 1b‐c) indicating a strain‐dependent viscoelastic behavior. The quasi‐static equibiaxial loading of the same specimens resulted in a nearly isotropic behavior (not shown here), exhibiting insignificant contrast between the stresses in the circumferential and longitudinal directions. Interestingly, the contrast in the relaxation behavior between the circumferential and longitudinal directions were similarly insignificant (Fig. 1b). Non‐equibiaxial loadings (15:30 and 13:50) showed significantly faster relaxation for the direction with smaller strains (Fig. 1b).ConclusionsMyocardial tissue viscoelasticity is an important behavior contributing to both diastolic and systolic cardiac function, which remains understudied, especially in case of structural heart diseases associated with impaired relaxation in the LV. Our study suggests that stress relaxation behavior is prominent in the LV myocardium and may exhibit different relaxation behavior depending on strain magnitudes and strain ratios along different directions. The level of anisotropy in stress relaxation was found to be similar to the level of anisotropy in the tissue quasi‐static behavior. These results serve to motivate further studies to fully characterize the viscoelastic behavior of LV myocardium and its contribution to the LV relaxation and filling in murine models of LV diseases.

Implementation and Development of Multi- Purpose Mechanical Machine

Abstract: This is paper presents the concept of ‘’Multi-Purpose Mechanical Machine’’ mainly carried out for production based industries. Industries are basically meant for Production of useful goods and services at low production cost, machinery cost and low inventory cost. Today in this world every task have been made quicker and fast due to technology advancement but this advancement also demands huge investments and expenditure, every industry desires to make high productivity rate maintaining the quality and standard of the product at low average cost. So in this project we have a proposed a machine which can perform operations like drilling, cutting, grinding some lathe operations at different working centers simultaneously which implies that industrialist have not to pay for machine performing above tasks individually for operating operation simultaneously. In this machine we are actually giving drive to the main shaft to which a bevel gear is attached, all four shafts have a bevel gear attached to each other to form a differential mechanism, and three of the four operations are both engageable and disengageable. Keyword: Multipurpose, Power transmission, Concurrent Engineering, FMS (Flexible Manufacturing System), Cutting.

Effectiveness of using the Mask with Innovative Nutrition Adaptor of Non-Invasive Mechanical Ventilation Machine for Patients with COVID-19

Background: Oral feeding of COVID-19 patients receiving NIMV is not possible due to the drastic demand for oxygenation. Removal of the mask for feeding is not possible.The presence of the innovative nutritional adaptor in the non-invasive ventilation mask(NA-NIMV) enables eating mixed foods and liquids through the mouth without the need to remove the mask, contrary to what happens in the standard hospital mask(SH-NIMV) where the mask is removed for feeding or using parenteral nutrition, and the use of the NA-NIMV does not cause air leakage during its use and thus maintains the level of oxygen saturation, respiratory rate, and heart rate. The objective of this study was designed to determine the effect of the mask with the innovative nutritional adaptor of NIVM (NA-NIMV) on the nutritional status of patients with COVID-19 in the ICU concerning air leakage, oxygen saturation (SPO2), respiratory rate (RR), and pulse rate (PR). Design: A crossover randomised controlled trial (RCT ) design was used to accomplish the aforementioned goals. Methods: A randomised sample of 24 patients with Covid-19 who were hospitalized in the ICU in two public hospitals, in Baghdad city. we include adult patients infected with COVID-19 who required NIV with (SH-NIMV) and (NA-NIMV), the intervention was: every patient received two interventions, apply (SH-NIMV) for 24hrs and received (NA-NIVM )for 24hrs. The outcomes of the endeavour were the amount of nutrition provided Calculated according to ESPEN guidelines, air leakage, SPO2, RR, and PR during each intervention. Results: A significant statistical difference between calories provided during apply (SH-NIMV) (Average Required calories= 1917, Mean Difference=1644.417* , Average Provided=272 = 14% from total calories need) and NA-NIVM(Average Required calories= 1917, Mean Difference=110.583* Average Provided=1806 = 94% from total calories need), a proteins (SH-NIMV) (Average Required proteins = 82.82917g Mean Difference=66.075*g , Average Provided=17g = 20% from total proteins need) and NA-NIVM(Average Required proteins = 66.075*g, Mean Difference=4.188*, Average Provided=79 = 95% from total proteins need), the mean differences between SH-NIMV and NA-NIMV in SPO2 Sig. (2-tailed = .0001), RR Sig. (2-tailed = .0001), air leakage Sig. (2-tailed = .0001), RR Sig. (2-tailed = .0001), PR Sig. (2-tailed = .001).Conclusion: Large amounts of calories and proteins while maintaining the absence of air leakage, SPO2, RR, and PR when using the NA-NIMV contrarily when using the SH-NIMV. Recommendation: manufacture a mask with a nutritional adaptor (NA-NIMV) according to the researchers’ design. Recourse to the NA-NIMV in the ICU for patients undergoing NIMV. Trail Registration: Clinical Trial Registry https://www.irct.ir/ reference number (IRCT20211022052840N1). Keywords: Mask, innovative Nutrition Adaptor, Non-Invasive Mechanical Ventilation Machine, COVID-19.

Experimental and Theoretical Analysis of Mechanical Properties of Graphite/Polyethylene Terephthalate Nanocomposites.

In this work, graphite nanoplatelets (GNP) were incorporated into poly (ethylene terephthalate) (PET) matrix to prepare PET-GNP nanocomposites using a melt compounding followed by compression moulding and then quenching process. Both static and dynamic mechanical properties of these quenched materials were characterized as a function of GNP contents using dynamic mechanical thermal analysis (DMTA) and tensile machine, respectively. The results demonstrated that the addition of GNP improved the stiffness of PET significantly. Additionally, the maximum increase in the storage modulus of 72% at 6 wt.% GNP. The incorporation of GNP beyond 6 wt.% into PET decreases the storage moduli, but they remain higher than pure PET. The observed reduction could be due to agglomeration, resulting in poorer dispersion and distribution of higher levels of GNP into the PET matrix. In contrast to the results for moduli, tensile strength and elongations at break reduce with increasing the GNP content. For example, tensile strength reduced from ∼46 MPa (neat PET) to ∼39 MPa (−15%) for the nanocomposites containing 2 wt.% GNP. This reduction is accompanied by a decline in elongation at break from ∼6.3 (neat PET) to ∼3.4 (−46%) for the same nanocomposites. Such reductions are followed by a gradual decrease in upon further addition of GNP. These reductions indicate that increasing GNP loadings, results in brittleness in nanocomposites. In addition, it was found that quenched PET and composite samples were not fully crystallized after processing and therefore (cold) crystallized during the first heating cycle DMTA, as indicated by a rise in storage moduli above the glass transition temperature during the DMTA first heat. Furthermore, mathematical models based on non-linear theories are developed to capture the experimental data. For this, a set of mechanical stress-strain data is used for model parameters’ identification. Another set of data is used for the model validation that demonstrates good agreements with the experimental study.

Deep Cryogenic Treatment Characteristics of a Deformation-Processed Cu-Ni-Co-Si Alloy.

This paper investigated the influence of deep cryogenic treatments (DCT) on the tensile strength, elongation to fracture and conductivity of a deformation-processed Cu-Ni-Co-Si alloy. The tensile properties were measured using a mechanical testing machine. The conductivity was evaluated using a low-resistance tester. The microstructure and precipitated phases were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), an energy dispersive spectrometer (EDS) and an X-ray diffractometer (XRD). The tensile strength, elongation to fracture and conductivity of the Cu-1.34Ni-1.02Co-0.61Si alloy before and after cold rolling at 47% reduction increased with increasing DCT time and tended to be stable at about 36 h. The microstructure became more uniform after the DCT. The grain size was refined and was smallest after DCT for 48 h. The DCT promoted the precipitation of the solid solution elements Ni, Co and Si from the Cu matrix to form many fine and evenly distributed 20–70 nm spherical second-phase particles in the grains and grain boundaries.

Symmetry and Asymmetry in the Fluid Mechanical Sewing Machine

The ‘fluid mechanical sewing machine’ is a device in which a thin thread of viscous fluid falls onto a horizontal belt moving in its own plane, creating a rich variety of ‘stitch’ patterns depending on the fall height and the belt speed. This review article surveys the complex phenomenology of the patterns, their symmetries, and the mathematical models that have been used to understand them. The various patterns obey different symmetries that include (slightly imperfect) fore–aft symmetry relative to the direction of belt motion and invariance under reflection across a vertical plane containing the velocity vector of the belt, followed by a shift of one-half the wavelength. As the belt speed decreases, the first (Hopf) bifurcation is to a ‘meandering’ state whose frequency is equal to the frequency Ωc of steady coiling on a motionless surface. More complex patterns can be studied using direct numerical simulation via a novel ‘discrete viscous threads’ algorithm that yields the Fourier spectra of the longitudinal and transverse components of the motion of the contact point of the thread with the belt. The most intriguing case is the ‘alternating loops’ pattern, the spectra of which are dominated by the first five multiples of Ωc/3. A reduced (three-degrees-of-freedom) model succeeds in predicting the sequence of patterns observed as the belt speed decreases for relatively low fall heights for which inertia in the thread is negligible. Patterns that appear at greater fall heights seem to owe their existence to weakly nonlinear interaction between different ‘distributed pendulum’ modes of the quasi-vertical ‘tail’ of the thread.

Environment- and Surface-Sensitive Effects on Mechanical Properties and Machinability of Solid Material : Part 1―Rehbinder Effect and the Others―

Environment- and Surface-Sensitive Effects on Mechanical Properties and Machinability of Solid Material : Part 1―Rehbinder Effect and the Others―

Electric Press Machine by Using Stepper Motor

Abstract: In ancient times material was shaped manually using hand hammers. Later on, big hammers were used to press large quantities of material at a time or to press a thick metal workpiece. Then after steam power and windmills were utilized to operate the large steam hammers. Prior to the invention of the machine press, workers were required to manually hammer metal by hand to change the shape of materials. After that, it cannot able used to change the shape of large or big size material, and itit’shysically ineffective. The steam hammer was developed around the mid – the 1800s and is also known as a drop hammer, the steam hammer or drop hammer was essentially an early version of the modern-day machine press. The only difference is that the steam hammer was powered by steam, whereas most modern-day machine presses are powered by hydraulics and electricity. Now day world, we are normally using a mechanical press machine and hydraulic press machine. In this paper, we are explaining about electric press machine by using stepper motor. Keywords: Arduino UNO R3, TB6600 4A Stepper Motor Driver, Permanent magnet Stepper Motor, SMPS (switched-mode power supply)

Study on the mechanical characteristics and damage evaluation of concrete-rock combination after high temperatures exposure

Concrete-rock combination (CRC) plays an important role in ensuring the safety and stability of the engineering (such as geothermal exploration, the production well, and radioactive waste storage) under high-temperature mechanical coupling conditions. In this study, a mechanical testing machine and an acoustic emission system were applied to investigate the mechanical properties of CRC after treatment at different temperatures (25 °C, 100 °C, 300 °C, 500 °C and 700 °C). A new theoretical model was established to study the thermal damage evolution. Meanwhile, the experimental results demonstrate that the peak strength of CRC is 36.6% for rock, and the peak strength of CRC is 129.6% relative to the concrete. When the temperature ranges from 25 °C to 500 °C, the stiffness decreases slowly, but above 500 °C, the stiffness decreases significantly. Additionally, the AE monitoring can well capture the damage location and microcrack process of CRC during the mechanical loading process after exposure to high temperatures. Finally, the theoretical values of the damage constitutive model are consistent with the experimental data, which verifies the validity of the damage model. Our new findings contribute to a better experimental and theoretical basis for CRC using complex environmental engineering.

Probing mechanical properties of graphene oxide/epoxy composites based on nano indentation technique

The silanized graphene oxide (KH-GO) with different mass fractions was dispersed in epoxy resin by a solution blending method and resin transfer molding process. The nano indentation method was used to test the micromechanical properties of GO/epoxy composites with different mass fractions, and the effect of GO on the hardness of epoxy matrix composites was quantitatively determined, and the influence of adding KH-GO on the thermal mechanical and bending properties of epoxy resin was discussed by dynamic thermal mechanical and universal strength machine tests. The experimental results show that the thermal and mechanical properties of composites are improved with the increase of the amount of KH-GO. Especially, when the content of KH-GO was 0.3%, the bending strength (125.4 MPa), hardness (281.0 MPa), and glass transition temperature (99.6°C) of composites reached the highest. It was proved that the composites showed its excellent performance and the silane coupling agent was successfully grafted to the graphene oxide by covalent bond, which effectively improved the interface compatibility of the reinforcing body and the matrix and was related to good dispersibility in the epoxy resin. This method is simple and effective, providing a certain reference value for the enhancement of the mechanical properties of the next generation of nanocomposites.

Evaluation of Mechanical and Electrical Performance of Aging Resistance ZTA Composites Reinforced with Graphene Oxide Consolidated by SPS.

This paper presents a study of Al2O3–ZrO2 (ZTA) nanocomposites with different contents of reduced graphene oxide (rGO). The influence of the rGO content on the physico-mechanical properties of the oxide composite was revealed. Graphene oxide was obtained using a modified Hummers method. Well-dispersed ZTA-GO nanopowders were produced using the colloidal processing method. Using spark plasma sintering technology (SPS), theoretically dense composites were obtained, which also reduced GO during SPS. The microstructure, phase composition, and physico-mechanical properties of the sintered composites were studied. The sintered ZTA composite with an in situ reduced graphene content of 0.28 wt.% after the characterization showed improved mechanical properties: bending strength was 876 ± 43 MPa, fracture toughness—6.8 ± 0.3 MPa·m1/2 and hardness—17.6 ± 0.3 GPa. Microstructure studies showed a uniform zirconia distribution in the ZTA ceramics. The study of the electrical conductivity of reduced graphene oxide-containing composites showed electrical conductivity above the percolation threshold with a small content of graphene oxide (0.28 wt.%). This electrical conductivity makes it possible to produce sintered ceramics by electrical discharge machining (EDM), which significantly reduces the cost of manufacturing complex-shaped products. Besides improved mechanical properties and EDM machinability, 0.28 wt.% rGO composites demonstrated high resistance to hydrothermal degradation.

Novel polymethyl methacrylate modified with metal methacrylate monomers: biological, physicomechanical, and optical properties

This study sought to evaluate the physical and antimicrobial properties of a thermopolymerizable acrylic resin (PMMA) modified with metallic methacrylate monomers -zirconia (ZM), tin (TM), and di-n-butyl (DNTMB) methacrylates. Color stability was evaluated before and after immersion of samples in a staining solution by a digital spectrophotometer. The mechanical brushing test was evaluated by the roughness test. The flexural strength test used a mechanical testing machine. Human keratinocytes were used to assess cell viability and the biofilm formation assay was carried out for 5 days, in a microcosms model after one year of specimen storage. For statistical analysis, the method chosen was based on adherence to the normal distribution model and equality of variances (p < 0.05). The addition of DNTMB to PMMA promoted great antimicrobial action, acceptable cytocompatibility, without hampering the physical-mechanical properties of the commercial material. Therefore, the modified PMMA proved to be a promisor alternative to conventional resins. This study sought to evaluate the physical and antimicrobial properties of a thermopolymerizable acrylic resin (PMMA) modified with metallic methacrylate monomers -zirconia (ZM), tin (TM), and di-n-butyldimethacrylate-tin (DNTMB) methacrylates. Color stability was evaluated before and after immersion of samples in a staining solution using a digital spectrophotometer. The mechanical brushing test was evaluated by the roughness test. The flexural strength test used a mechanical testing machine. Human keratinocytes were used to assess cell viability and the biofilm formation assay was carried out for 5 days in a microcosm model after one year of specimen storage. For statistical analysis, the method chosen was based on adherence to the normal distribution model and equality of variances (p < 0.05). The addition of DNTMB to PMMA promoted great antimicrobial action, acceptable cytocompatibility, without hampering the physical-mechanical properties of the commercial material. Therefore, the modified PMMA proved to be a promising alternative to conventional denture base resins for dental use.

Выбор гидравлической схемы для оптимальной работы забоечной машины

Blasthole stemming has a major impact on blasting operations. Depending on the stemming material, different types of equipment are used, one of which is described in this article. The article presents the ZM-7-G stemming truck manufactured by AZOTTEKH LLC, which is designed for mechanized stemming with loose material. The stemming truck complements a range of machines for mechanization blasting operations and improves the blasting efficiency, reducing the flyrock zone and enhancing the environmental situation in the quarry areas. An optimal hydraulic circuit is selected based on this model and taking into account the hydraulic fluid flow rate and pressure of the safety valves set to a specific value. Implementation of the hydraulic circuit with separated hydraulic fluid flows ensures efficient maintenance and economical consumption of the hydraulic fluid, correct operation of the crane with the rated capacity, as well as safe operation of all actuating mechanisms. Conclusions are made on operation of the telescopic crane with a clamp bucket, and a description of the selected hydraulic system is provided.

Effect of Fiber Type and Content on Mechanical Property and Lapping Machinability of Fiber-Reinforced Polyetheretherketone.

Polyetheretherketone (PEEK) is a novel polymer material with excellent material properties. The hardness and strength of PEEK can be further improved by introducing fiber reinforcements to meet the high-performance index of the aerospace industry. The machinability will be influenced when the material properties change. Therefore, it is crucial to investigate the influence of material properties of the fiber-reinforced PEEK on machinability. In this paper, the main materials include pure PEEK, short carbon-fiber-reinforced PEEK (CF/PEEK), and short glass-fiber-reinforced PEEK (GF/PEEK). The effects of the fiber type and mass fraction on the tensile strength, hardness, and elastic modulus of materials were discussed using the tensile test and nanoindentation experiments. Furthermore, the fiber-reinforced PEEK lapping machinability was investigated using lapping experiments with abrasive papers of different mesh sizes. The results showed that the hardness and elastic modulus of PEEK could be improved with fiber mass fraction, and the tensile strength of CF/PEEK can be improved compared with that of GF/PEEK. In terms of lapping ability, the material removal rates of the fiber-reinforced materials were found to be lower than the pure PEEK due to the higher hardness of the fiber. During the lapping process, the material removal methods mainly included the ductile deformation or desquamation of reinforcing fiber and ductile removal of the PEEK matrix. The lapped surface roughness of PEEK material can be improved by fiber reinforcement.

Gas Dispersion Characteristics in a Novel Jet-Stirring Coupling Flotation Device

A jet-stirring coupling flotation device (JSCFD) was proposed to analyze the distribution characteristics of gas holdup and bubble Sauter mean diameter (D32) in a gas–liquid system under various parameters. Results of studies suggested that the gas holdup increased with methyl isobutyl carbinol concentration, feeding pressure, and gas flow rate. The maximal gas holdup in the absence of the stirring impeller was ∼23.29% for the bubble size of 0.59 mm, which was considerably lower than the maximum gas holdup of 66.27% for the bubble size of 0.31 mm in the presence of the stirring impeller; the gas holdup was raised by ∼43% due to the bubbles torn by the stirring impeller to generate extensive smaller size bubbles and increase the content of small bubbles, and increasing the stirring impeller speed was conducive to reduce the bubble size and increase the gas holdup in JSCFD. Compared to traditional flotation machines, the size of bubbles generated by JSCFD was smaller, and the gas holdup distribution conforms to the following order: JSCFD > mechanical flotation machine > column flotation, which demonstrated that the JSCFD had a noticeable effect on increasing the gas holdup and reducing the bubble size.

Research on the constitutive model of low-damage corn threshing based on DEM

The constitutive model of corn has an intense influence on the mechanical structure design and machine performance. In this paper, a creep property formula of corn-based on the Burgers model was proposed, which described the change process of the stress–strain trait of corn grain with time. Then, the mathematical model of the “corn-mechanical” interaction system was then established based on the Hertz-Mindlin no-slip model. The kinematic and dynamic formulas of corn ear under the action of threshers were deduced, and the “corn-corn” contact characteristics based on Hertz-Mindlin with bonding model were analyzed. Moreover, a new discrete element model construction method of the corn ear was proposed through particle filling and splicing methods. The simulation experiment was carried out in EDEM to verify the constitutive model and discrete element model of corn ear. The results showed that the particle filling model could better explain the mechanism of corn ear threshing and obtain the force of each corn grain during threshing. The average velocity of corn ear was 55.2 m/s, the maximum value was 216.7 m/s, and the minimum value was 16.2 m/s, while the average normal force was 201.7 N, the maximum force was 342.0 N, and the minimum force was 104.2 N respectively, it verified the feasibility and accuracy of models. Finally, the field experiment was carried out to verify the simulation results, and the corn grain broken rate was 2.16%. These results fill the blank of fundamental theoretical research on the design of corn ear threshing devices and provide a reference for the optimal design of other crop production equipment.

Applying AES algorithm for secure data transmission between Sensor node and LoRa Gateway to Web Server

Lora Gateway is an intermediary device that can connect devices in the IoT system. IoT is the Internet of Things, consisting of a system of interrelated digital and mechanical devices and machines, capable of transmitting data over a network without requiring human-computer interaction. Lora is a long distance wireless communication technology that enables communication over a wide range between devices. Through this device, the Sensor nodes in the IoT system can transmit and receive data by LoRa waves to the Gateway and by Wifi/3G to the web server via the Internet. Data communicates in the internet environment, so important information needs to be protected by data encryption. This paper presents research and application of 128-bit AES symmetric encryption algorithm in LoRa wide area sensor network to secure data transmission between IoT devices and web server through LoRa Gateway device. The research team has designed and built models for testing sensor stations with integrated humidity and temperature sensors, LoRa Gateway integrating Lora module and wifi/3G module, developing the interface on web server with decoding, monitoring, and data storage features, and proposing a solution with AES encryption algorithm and architecture applied in the development of embedded software for LoRa module. The research results are tested on the model to test the encryption, data transmission, and decryption functions in applications for IoT LoRa Gateway systems. With this initial research, it is possible to apply the AES algorithm to secure data transmission in IoT Gateway systems.

An Experimental Study and Mathematical Modeling of Vibration Transfer in Pistachio Trees Using an Inertia-Type Trunk Shaker and Field-Adapted Wireless Sensors

Trunk shakers are the most widely used mechanical harvesting machines for harvesting nut trees, including pistachio in California. Improvement of these machines requires a better understanding of the shaking dynamics of the existing trunk shakers during harvest. In this study, the effects of four different shaking patterns on three sizes of pistachio trees of different ages, shapes, and sizes were investigated under field conditions. The vibration acceleration of the real pistachio tree was measured using a wireless network of 3-axis accelerometers installed on the shaker head and different parts of the trees during the shaking harvest. Changes in acceleration and the effect of tree morphology on the magnitude of acceleration in each pattern are presented and discussed. A new location index λ, which is based on the distance of the sensor from the shaking point and diameter of the branch at each sensor location, is introduced. This study focused on mathematical modeling of the variation and distribution of the acceleration throughout the tree canopy. The sensor location index, relative force ratio (RFR), and relative kinetic energy ratio (RKER) were defined to better understand the energy damping in each part of the tree. The results showed that the relationship between the acceleration peaks and the sensor location index could be expressed by a third-degree polynomial function with an acceptable coefficient of determination. Under different shaking patterns, similar changes in the RFR of the tree at different locations and for different trees were observed. This finding indicates that the vibration force is significantly damped as the distance from the shaker clamps increases. However, the RKER values at the same shaking pattern result in different effects at different points on the branches according to tree morphology.

Effect of compacting conditions on the viscoelastic properties of banana leaf waste and briquette quality.

This study evaluated the effects of the temperature and pressure used when compacting banana leaves on viscoelastic properties and briquette quality. Banana leaves with 12.4% of humidity were milled at two ranges of average particle size. The briquetting was carried out in a cylinder-piston device coupled to a universal mechanical test machine, under different compacting temperatures (30 and 120°C) and pressures (20, 40 and 60MPa). Several parameters, including compacting module, porosity index, final density, critical density, compacting energy, compression ratio, higher heating value, and energy density, were investigated. The banana leaf particles smaller than 1.7mm performed better during compaction, with low compacting resistance. Temperature showed less influence on final density than pressure. The increase of pressure contributed to decreasing the compacting module and to achieving denser briquettes. It was not necessary to apply high temperature to obtain briquettes with high final density and energy density. The optimum briquetting process parameters identified can be used to produce briquettes from banana leaves at an industrial scale with an extruder. Briquetting adds value to banana leaf waste and reduces environmental pollution.