Influence of roundness error screw on running characteristics of sliding bearing based on SDT

In order to study the influence of roundness error on the oil film characteristics of journal bearing rotor system, a dynamic model of journal bearing rotor system with roundness error was established, and a new generalized roundness error equation is derived based on the small displacement screw (SDT) theory. And the influence of roundness error screw parameter dx represented by SDT on critical speed and stability of sliding bearing is analyzed emphatically. The results show that the existence of journal roundness error is beneficial to the bearing capacity and stability of sliding bearing rotor system to a certain extent, and with the increase of roundness error screw parameter, its promoting effect is more obvious; At the same time, the critical speed of the system will increase with the increase of screw parameter, especially when eccentricity ε>0.6; And when Sommerfeld number S>0.6, the roundness error of journal has little influence on stability.

Karakteristik Poli Asam Laktat Glikolat (Kajian Rasio Asam Laktat Limbah Aren-Asam Glikolat)

Polimer Poli Asam Laktat Glikolat (PLGA) merupakan salah satu jenis polimer yang telah disetujui FDA dan EMA untuk penggunaan biomedik. Kelebihan PLGA yaitu biokompatibilitas, biodegradabilitas, fleksibilitas, dan efek samping yang minimal. PLGA telah dikembangkan untuk penggunaan medis namun pemenuhannya masih berupa impor. Oleh karena itu, pada penelitian ini monomer asam laktat dari limbah pati aren dan asam glikolat dengan rasio LA:GA = 75%:25%; 90%:10%; 95%:5%; direaksikan secara Ring Opening Polymerization (ROP) dengan bantuan katalis Sn(II) Oktoat membentuk PLGA. PLGA hasil kemudian ditambahkan PVA, dengan rasio PLGA:PVA 3:2; 3:3; 3:4; dan 3:5 dengan metode solution casting membentuk film. Penelitian dilakukan secara eksperimental dengan Rancangan Acak Lengkap (RAL) faktorial. Hasil penelitian menunjukkan adanya kombinasi rasio LA:GA dan rasio penambahan PVA mempengaruhi karakteristik film PLGA. Hasil kekakuan dan Modulus Young film PLGA tertinggi pada kombinasi penambahan rasio LA:GA = 75%:25% dan penambahan rasio PLGA:PVA =3:4. Biodegrabilitas film PLGA terbaik pada kombinasi penambahan rasio LA:GA 90%:10% dan penambahan rasio PLGA:PVA 3:4. Film PLGA memiliki biokompatibilitas yang baik pada semua rasio LA:GA, dengan penambahan rasio PLGA:PVA lebih dari 3:2. Hasil film PLGA memiliki morfologi permukaan paling halus pada rasio penambahan PLGA : PVA 3:2, dan memiliki struktur semi kristalin.Lactic Glycolic Acid Polymer (PLGA) is a type of polymer that has been approved by the FDA and EMA for biomedical use. The advantages of PLGA are biocompatibility, biodegradability, flexibility, and minimal side effects. PLGA has been developed for medical use but fulfillment is still imported. Therefore, in this study, the lactic acid monomer from waste palm starch and glycolic acid with a ratio of LA: GA = 75%: 25%; 90%: 10%; 95%: 5%; reacted with Ring Opening Polymerization (ROP) with the help of a catalyst Sn (II) Octoate to form PLGA. The resulting PLGA was then added with PVA, with a ratio of PLGA: PVA 3: 2; 3: 3; 3: 4; and 3: 5 with the solution casting method forming the film. This research was conducted experimentally with a factorial completely randomized design (CRD). The results showed that the combination of LA: GA ratio and PVA addition ratio affected the PLGA film characteristics. The results of stiffness and Young's Modulus of PLGA film were highest in the combination of addition of the ratio of LA: GA = 75%: 25% and the addition of the ratio of PLGA: PVA = 3: 4. The best PLGA film biodegradability was combined with the addition of the ratio of LA: GA 90%: 10% and the addition of the PLGA: PVA ratio 3: 4. PLGA film has good biocompatibility in all LA: GA ratios, with the addition of a PLGA: PVA ratio of more than 3: 2. The results of the PLGA film had the smoothest surface morphology at the ratio of addition of PLGA: PVA 3: 2, and had a semi-crystalline structure.

Thin-film Characterization

The third intended application for the proposed dispersion-encoded low-coherence interferometry is the evaluation of thin-film characteristics on substrate materials. Due to the usage of thin-film technologies in high-volume production in e.g. the photovoltaics and semiconductor industry, process monitoring becomes relevant in order to ensure functional parameters such as solar cell efficiency, [289]. In this context, film thickness as well as film homogeneity over large areas are important criteria for quality assurance.

Development and Characterization of Semi-Refined Iota Carrageenan/SiO2-ZnO Bionanocomposite Film with the Addition of Cassava Starch for Application on Minced Chicken Meat Packaging

In the current study, film based on semi-refined ι-carrageenan/cassava starch (SRiC/CS) incorporated with SiO2-ZnO nanoparticles was fabricated and characterized to deal with serious environmental problems resulting from plastic packaging materials. This study aimed to evaluate film properties with the variation of SRiC/CS proportions of bionanocomposite films for application to minced chicken meat packaging. Increasing CS portion contributed to increased transparency, reduced surface roughness, and decreased mechanical properties of films. The variable significantly (p < 0.05) increased the water vapor permeability (WVP) and reduced the water solubility of films. The incorporation of the nanoparticles significantly (p < 0.05) increased UV screening, decreased WVP, and enhanced the antimicrobial activity of films. Furthermore, the substitution of 0.5 wt% (weight percentage) CS provided the best film characteristics. Based on the color and the total volatile base nitrogen (TVBN) results, SRiC film incorporated with the nanoparticles preserved minced chicken quality up to six days. Thus, the developed films are desirable for biodegradable food packaging.

The Effect of Slotted Hole on Minimum Oil Film Thickness of Piston in Radial Piston Hydraulic Motor

The cam-lobe radial-piston hydraulic motor, a multistroke low-speed high-torque motor, is widely used in large rotating machines such as winches, shield machines, and shredders, etc. There is a slotted hole on its pistons to reduce inertial force, which can simultaneously affect piston deformation. Unfortunately, piston deformation will also have an obvious impact on the oil film characteristics of the interface between pistons and cam rollers. Accordingly, in this paper, a coupled model, which combines the unsteady elastohydrodynamic lubrication model and a structural mechanics model, is established. Based on the model, the effect of the slotted hole on the minimum oil film thickness is analyzed through the dynamic simulation. The simulation results show that the slotted hole alters the oil film shape and pressure distribution. As a result, the minimum oil film thickness increases. This study could provide valuable guidance for further optimizing the piston of radial piston hydraulic motor.