Pengaruh Arah Pemakanandan Sudut Permukaan Bidang Kerja Terhadap Kekasaran Permukaan Material S45c Pada Mesin Frais Cnc Menggunakan Ballnose Endmill

Nilai sebuah produk dapat diindikasikan salah satunya adalah kualitas permukaan. Bahan baja S45C banyak dipakai pada konstruksi mesin sehingga sering mengalami perlakuan proses pemesinan. Proses pemesinan mempunyai kualitas kehalusan (nilai kekasaran) yang berbeda terutama pada mesin frais CNC. Penelitian ini bertujuan untuk mengetahui pengaruh variasi arah pemakanan dan sudut permukaan bidang kerja pada proses mesin frais CNC pada material S45C menggunakan jenis alat potong ballnose endmill terhadap nilai kekasaran. Metode penelitian yang digunakan dengan memberikan variasi arah pemakanan searah 45°, searah 90° dan berputar konstan sumbu Z dengan variasi sudut permukaan bidang kerja sebesar sebesar 0, 30, 45 dan 60°. Pergeseran alat potong sebesar 0,3 mm berputar pada 3000 rpm dan feeding 429 mm/menit dengan kedalaman pemakanan 0,4 mm. Pengujian kekasaran hasil pemesinan menggunakan TR 100 Surface Roughness Tester dan diamati menggunakan mikroskop digital USB perbesaran 800x. Hasil yang didapat nilai kekasaran yang paling kecil (halus) adalah sebesar 0,85 µm terjadi pada arah pemakanan searah 45° bertemu dengan sudut bidang permukaan kerja 30°. Pada arah pemakanan searah 90° dan searah 45°nilai kekasaran semakin meningkat (semakin kasar) sebanding dengan bertambahnya sudut permukaan bidang kerja sedangkan pada arah pemakanan berputar konstan sumbu Z nilai kekasaran semakin menurun (semakin halus) berbanding terbalik dengan bertambahnya sudut permukaan bidang kerja

Flame propagation and burning rates of methane-air mixtures using schlieren photography

Different methodology have been shown to produce different results for Markstein length and laminar burning velocity of methane-air mixture. This study attempts to determine the aforesaid parameters using the newly developed closed vessel combustion chamber with Schlieren photography. Markstein length and burning rate of methane-air mixture was determined under the initial pressure of 1 atm, temperature range of 298-302K and equivalence ratio range of 0.7-1.3. Experiments were performed in a centrally ignited 29.16L cylindrical constant volume combustion chamber. Ignition energy was set at 25mJ for each experiment. The images of spherically expanding flame were recorded using Schlieren photography technique at a speed of 2000 frame per second. Analysis of the flame area yield flame radii from which the flame speed and stretch rate could be obtained. These parameters would allow the determination of Markstein length and burning rate of the flame. Results show that Markstein length magnitude increases proportionally with equivalence ratio with a magnitude ranging from 0.125cm to 0.245cm. Maximum burning rate occurs at equivalence ratio of 1.1 with a magnitude of 0.366 m/s. Flame of each equivalence ratio also exhibits fluctuation arising from acoustic disturbance. This disturbance becomes more apparent at higher equivalence ratio

Perbedaan Skor Plak Gigi, Ph Saliva, Dan Status Oral Hygiene Pada Pemakai Dan Bukan Pemakai Alat Ortodonti Cekat

Orthodontic appliances can have the effect of changing the environment of oral cavity and composition of oral flora, changes in the amount of plaque, pH of salivary and oral hygiene which can cause dental and oral diseases such as dental caries and periodontal disease. The aim of this studyis to know the difference of dental plaquescore, salivary pH,and oral hygiene status between users and non users of fixed orthodonticappliance. This type of research is an observational analytic with cross sectional design. Subjects in this study amounted to 100 respondents consisting of two groups of users and non users of fixed appliance orthodontic. The technique sampling is proportional stratified random sampling. Identification of dental plaquewere measured by disclosing solution, salivary pH were measuredby Universal CG and oral hygiene status were measured by summing debris score and calculus score from each subject. The result showed that the difference of plaque scores between the users and non users of fixed appliance orthodontic with p = 0,769, the difference of saliva pH between users and non users of fixed appliance orthodontic with p = 0,264, and the difference of oral hygiene status between users and non users of fixed appliance orthodontic with p = 0.397. Conclusion: there was no significant difference of dental plaquescore, salivary pH,and oral hygiene status between users and non users of fixed orthodonticapplianceof students of Economics and Business Diponegoro University

Modeling of occupant's head movement behavior in motion sickness study via time delay neural network

Passengers are more susceptible to experiencing motion sickness (MS) than drivers. The difference in the severity of MS is due to their different head movement behavior during curve driving. When negotiating a curve, the passengers tilt their heads towards the lateral acceleration direction while the drivers tilt their heads against it. Thus, to reduce the passengers’ level of MS, they need to reduce their head’s tilting angle towards the lateral acceleration direction. Designing MS minimization strategies is easier if the correlation between the head movement and lateral acceleration is known mathematically. Therefore, this paper proposes the utilization of a time delay neural network (TDNN) to model the correlation of the occupant’s head movement and lateral acceleration. An experiment was conducted to gather real-time data for the modeling process. The results show that TDNN manages to model the correlation by producing a similar output response to the actual response. Thus, it is expected that the correlation model could be used as an occupant’s head movement predictor tool in future studies of MS

Heat transfer enhancement and pressure drop for fin-and-tube compact heat exchangers with delta winglet-type vortex generators

Heat transfer rate, pressure loss and efficiency are considered as the most important parameters in designing compact heat exchangers. Despite different types of heat exchangers, fin-and-tube compact heat exchangers are still common device in different industries due to the diversity of usage and the low space installation need. The efficiency of the compact heat exchanger can be increased by introducing the fins and increasing the heat transfer rate between the surface and the surroundings. Numerous modifications can be applied to the fin surface to increase heat transfer. Delta-winglet vortex generators (VGs) are known to enhance the heat transfer between the energy carrying fluid and the heat transfer surfaces in plate-fin-and-tube banks, but they have drawbacks as well. They increase the pressure loss and this should be considered. In this paper, the thermal efficiency of compact heat exchanger with VGs is investigated in different variations. The angle of attack, the length and horizontal and vertical position of winglet are the main parameters to consider. Numerical analyses are carried out to examine finned tube heat exchanger with winglets at the fin surface in a relatively low Reynolds number flow for the inline tube arrangements. The results showed that the length of the winglet significantly affects the improvement of heat transfer performance of the fin-and-tube compact heat exchangers with a moderate pressure loss penalty. In addition, the results show that the optimization cannot be performed for one criterion only. More parameters should be considered at the same time to run the process properly and improve the heat exchanger efficiency

Experimental and Numeriacal Study of Moisture Moviment Inside an Air Conditioned Space

This research is concerned with a computational study to simulate a turbulent three –dimensional buoyancy recirculation flow in an air-conditioned space. The study includes the simulation of heat and moisture generated from an internal source inside the space. An experimental facility to study temperature and moisture distribution in an airconditioned space has also been designed, constructed and tested in a laboratory scale. A numerical procedure was carried out to solve the elliptic partial differential equations that govern the flow, heat and mass transfer in a finite –volume form. The finite -volume approach was applied to solve these equations using the upwind –differencing scheme. The SIMPLE iterative procedure [1] for solving the algebraic equations is employed in the present study. The proposed method is the line by line technique uses the Tri- Diagonal Matrix Algorithm (TDMA) as its basic unit. A modified version of a threedimensional elliptic computer code was used to simulate heat and moisture transfer generated from the internal source inside the space. A study of the flow, heat and mass transfer in air-conditioned space are used as test cases to justify the performance of the computational procedure. The temperature and moisture distribution were compared with predictions of previous researchers. The data from the experimental model was also used to verify the computational procedure predictions

Evaluation of residential grid-connected photovoltaic system as the potential energy source in Malaysia

Application of solar energy in Malaysia has been started in 1998. This country has a large potential of solar energy due to its location at equatorial region. The current energy consumption and demand in Malaysia is describes in this paper. The potential of solar energy in Malaysia is described together with the suitable photovoltaic construction. It also explains the plans conducted by Malaysia involving solar energy that covers investments and also projects involved such as Malaysia Building Integrated Photovoltaic (MBIPV). Simulation of grid-connected photovoltaic system in this study is performed using HOMER software. Finally, the potential of having a grid-connected PV system in a residential area is analyzed. The positive and negative findings in terms of cost and suitability of the system are explained

Potential of Residential Grid-Connected Photovoltaic System as the Future Energy Source in Malaysia

Malaysia has started the implementation of solarenergy harvesting in 1998. Located at equatorial region, Malaysia hasa large potential for solar energy. This paper examines the currentenergy consumption and demand in Malaysia. The potential of solarenergy harvesting in Malaysia is described together with the suitablephotovoltaic construction. It also explains the plans conducted byMalaysia involving solar energy that covers investments and alsoprojects involved such as Malaysia Building Integrated Photovoltaic(MBIPV). Finally, this paper analyses the potential of having a gridconnectedPV system in a residential area. The positive and negativefindings in terms of cost and suitability of the system are explaine

Multifunctional Silver-based Nanomaterials for Non-conventional Oral Cancer Therapy through Simultaneous LOX and Selective COX-2 inhibition

Neoplastic cells have co-opted inflammatory receptors and signaling molecules that potentiate inflammation. Activated inflammatory pathways lead to neo-angiogenesis, lymph-angiogenesis, immunosuppression, tumor growth, proliferation and metastasis. This cancer-sustaining inflammation is a critical target to arrest cancer growth. Multiple drug resistance, high cost, low oral bioavailability and serious side effects have rendered conventional cytotoxic chemotherapeutics less impressive. The aim of this research was to achieve cancer debulking and proliferation prevention by limiting ‘cancer-sustaining’ tumor niche inflammation through non-conventional oral approach employing anti-inflammatory agents and avoiding conventional cytotoxic agents. Synergistic anti-inflammatory agents, i.e. celecoxib as selective COX-2 inhibitor and montelukast as cysteinyl leukotriene receptor antagonist, were selected. Silver nanoparticles (AgNPs) were used as nanocarriers because of their efficient synergistic anti-neoplastic effects and excellent oral drug delivery potential. Specifically, selected drugs were co-conjugated onto AgNPs. Synthesized nanoparticles were then surface-modified with poly (vinyl alcohol) to control particle size, avoid opsonization/preferred cellular uptake and improve dispersion. Surface plasmon resonance analysis, particle size analysis, DSC, TGA, XRD, FTIR and LIBS analysis confirmed the successful conjugation of drugs and efficient polymer coating with high loading efficiency. In-vitro, the nanoparticles manifested best and sustained release in moderately acidic (pH 4.5) milieu enabling passive tumor targeting potential. In-vivo, synthesized nanoparticles exhibited efficient dose-dependent anti-inflammatory activity reducing the dose up to 25-fold. The formulation also manifested hemo-compatibility, potent anti-denaturation activity and dose-dependent in-vitro and in-vivo anti-cancer potential against MCF-7 breast cancer and Hep-G2 liver cancer cell lines in both orthotopic and subcutaneous xenograft cancer models. The anti-inflammatory nanoparticles manifested tumor specific release potential exhibiting selective cytotoxicity at cancerous milieu with slightly acidic environment and activated inflammatory pathways. The formulation displayed impressive oral bioavailability, sustained release, negligible cytotoxicity against THLE-2 normal human hepatocytes, low toxicity (high LD50) and wide therapeutic window. Results suggest promise of developed nanomaterials as hemo-compatible, potent, cheaper, less-toxic oral anti-inflammatory and non-conventional anti-cancer agents

Effects of nitrification inhibitor with organic manure and urea on protein and mineral contents in grain of Oryza sativa cv. MR219 cultivated in acid sulphate soil

Several approaches to improve grain nutritive values involve in increasing seed accumulation of protein and micronutrients in rice. Therefore, a study was conducted to select a suitable combination of dicyandiamide (DCD) with organic manure (OM) and urea to improve protein and mineral content in rice grain of MR219. The protein (9.07-12.50%) and Ca, Mg, Zn, Cu, Fe and Mn concentrations increased from 1.92 to 21.05, 3.56 to 18.25, 2.25 to 20.22, 9.14 to 25.66, 3.34 to 27.20 and 5.17 to 23.86%, respectively due to the application of DCD with urea and OM. Moreover, the highest content of protein in grain was obtained for the application of DCD with urea and oil palm compost (OPC). Iron and Mn contents were also highest for DCD with urea and OPC, but Ca, Mg, Zn and Cu contents were highest for DCD with urea and poultry dung (PD) and kept similarity with DCD with urea and OPC