PARTICLE TRACKING OF A SIMULATED MELT POOL OF SELECTIVE LASER MELTING

Metal additive manufacturing (AM) produces parts by addition as compared to subtraction of material. Selective laser melting (SLM) is an AM technique that prints objects layer-by-layer, selectively melting powders using a laser. The mechanical properties of SLM parts are affected by processing parameters and powder characteristics, both of which alter the molten melt pool flow field. Marangoni convection (M-flow) is a thermo-capillary mass transfer from a region of lower surface tension to a region of higher surface tension, referred to as a radially outward flow for SLM. However, in the presence of surface-active elements such as oxides and sulfides, the melt pool surface flow direction may shift from radially outward flow to radially inward flow (inverse M-flow). Balling and pores, the most common defects in SLM, have been correlated to the presence of inverse M-flow but the relation has yet to be quantified. In order to quantify the surface flow using high-speed melt pool videos, numerical simulations and algorithms for melt pool flow were developed. The surface flow of a melt pool was simulated as binary images created using a MATLAB script. A particle tracking algorithm developed in MATLAB, using various functions from the MATLAB Image Processing Toolbox, was used to track the surface oxide particles in the simulated binary images. Various factors that may affect the particle tracking algorithm, such as 1) the melt pool size, 2) the image pixel size, 3) the size and the number of surface oxides, 4) the flow type, and 5) the particle velocity, were varied in the simulated binary images. Experiments were designed and results analyzed against the numerical error measured to generate a model using Design Expert 12, a statistical design analysis software package. Design Expert 12 was used to determine the significance of each factor within the model. The ANOVA results demonstrated that particle velocity and flow type have significant influence on the error of measured displacement. The error increased with decreasing displacement of the particles being tracked in the melt pool simulation. Melt pool algorithm error has been quantified and validated against simulated data, therefore it can be used to analyze actual melt pool data with known confidence

Proučavanje četvrte generacije kvarkova i neutralnih struja koje mijenjaju okus

The decay of the fourth-generation down-type quark b\u27 → bγ and b\u27 → bg has been studied as an extension of the standard model using evolution of the mass-based fourth generation CKM matrix with CP violation phase equal to zero. Range of the masses of fourth generation down-type quark b\u27 and up-type quark t\u27 have been taken with due observance of the constraint imposed by the present experimental value of the ρ parameter, keeping in view the mass difference of the fourth generation quark doublet. The decay width of b\u27 → bγ also has been studied, however, with correction up to the leading QCD logarithms for six active flavours after the W boson, t and t\u27 quarks have been integrated out using operator product expansion. Strong interaction coupling constant is taken on matching scale of Z boson mass.Razmatraju se raspadi četvrte generacije kvarkova tipa ”dolje” b\u27 → bγ i b\u27 → bg kao proširenje standardnog modela, primjenom evolucije CKM matrice četvrte generacije zasnovane na masi, s fazom kršenja CP simetrije jednakom nula. Izabrali smo područje masa kvarkova četvrte generacije tipa ”dolje” b\u27 i tipa ”gore” t\u27 gledajući ograničenje koje postavlja sadašnja eksperimentalna vrijednost parametra ρ, drzeći u vidu razliku masa kvarkovskog dubleta četvrte generacije. Također se proučava širina raspada b\u27 → bγ, ali s popravkom do vodećih QCD logaritama za šest aktivnih okusa, nakon sto su W bozon, te t i t\u27 kvarkovi izintegrirani primjenom razvoja operatorskog umnoška. Konstanta jake interakcije uzela se je u skladu s masom Z bozona

Formulación y evaluación de vesículas de liposomas de baclofeno usando lecitina

I express my sincere regards and respect to RIC and Pharmaceutical Sciences of IKG Punjab Technical University, Jalandhar, for their support and kind cooperationIntroducción: El objetivo principal del presente estudio fue preparar y caracterizar la formulación liposomal de baclofeno para mejorar la efectividad de la formulación aplicada tópicamente. Método: Para la preparación de liposomas, se tomaron diferentes proporciones de lecitina, colesterol y etanol, pero la proporción de fármaco y ácido esteárico se mantuvo constante y se preparó mediante el método de inyección de etanol. Los liposomas se caracterizaron por tamaño de vesícula, forma de vesícula, eficacia de atrapamiento, estudios in vitro, estudios de estabilidad y estudios in vivo. Resultados: El tamaño promedio de partícula del liposoma formulado estuvo en el rango de 3.98 ± 0,45-4,24 ± 0,65 µm y se observaron pequeñas vesículas unilamelares con forma esférica. La eficiencia de atrapamiento de la formulación optimizada fue de 58,67 ± 0,81%. El % máximo de comportamientos acumulativos de liberación de drogas fue 67,66 ± 5,32% después de 10 h. la formulación almacenada a una temperatura de 4 ± 2 ° C muestra una mejor estabilidad (64,19±0,26) en comparación con la temperatura elevada. Se usaron ratones albinos suizos para el estudio in vivo y exhiben actividad relajante muscular en términos de no. de caídas del aparato de varilla giratoria (valor p = 0,001). Conclusiones: la formulación liposomal cargada de baclofeno ha mostrado actividad relajante del músculo esquelético en ratones, lo que sugiere la administración de baclofeno desde los liposomas en el rango terapéutico.Introduction: The main aim of present study was to prepare and characterize liposomal formulation of baclofen to improve the effectiveness of the topically applied formulation. Method: For the preparation of liposomes, different ratio of lecithin, cholesterol and ethanol were taken but ratio of drug and stearic acid were kept constant and prepared by ethanol injection method. Liposomes were characterized for vesicle size, vesicle shape, entrapment efficiency, in vitro studies, stability studies and in vivo studies. Results: The average particle size of formulated liposome was in the range of 3.98±0.45-4.24±0.65 µm and small unilamellar vesicles with spherical in shape observed. Entrapment efficiency of optimized formulation was 58.67±0.81 %. The maximum % cumulative drug release behaviours were 67.66±5.32 % after 10 h. formulation stored in 4±2 °C temperature shows better stability (64.19±0.26) compared to elevated temperature. Swiss albino mice were used for the in vivo study and exhibit muscle relaxant activity in terms of no. of falls from rota rod apparatus (p value =0.001). Conclusions: Baclofen loaded liposomal formulation have shown skeletal muscle relaxant activity in mice suggesting delivery of baclofen from liposomes in the therapeutic range

A SOLUTION TO SELECTIVE FORWARD ATTACK IN WIRELESS SENSOR NETWORK

Purpose of Study: Wireless mesh network represents a solution to provide wireless connectivity. There are some attacks on wireless sensor networks like black hole attack, sinkhole attack, Sybil attack, selective forwarding, etc. In this paper, we will concentrate on a selective forwarding attack. Selective Forwarding Attack is one of the many security threats in wireless sensor networks that can degrade network performance. An adversary on the transmission path selectively drops the packet. The adversary same time transfers the packet, while on a few occasions it drops the packet. It is difficult to detect this type of attack since the packet loss may be due to unreliable wireless communication. The proposed scheme is based on the trust value of each node. During data transmission, a node selects a downstream node that has the highest trust value, which is updated dynamically based on the number of packets a node has forwarded and dropped. Methodology: A comparative methodology is used in all existing schemes. We compared our scheme with the existing scheme and found that the packet loss in the proposed scheme is much less than the existing scheme. Result: We showed that our scheme essentially detects malicious nodes for each possible scenario. Regarding communication overhead, our scheme is more efficient than typical multipath schemes. Also, by utilizing an existing routing protocol which is secure against sinkhole attacks, our scheme also provides security against sinkhole attacks

LIGHT SCATTERING STUDY OF IRREGULAR PARTICLES WITH ARBITRARY SIZE, SHAPE, AND COMPLEX REFRACTIVE INDEX

Doctor of PhilosophyDepartment of PhysicsChristopher M SorensenWe investigated light scattering due to irregularly shaped aerosol particles with diverse shapes, sizes, and complex refractive indices. We have designed and developed a light scattering setup based on a novel optical scheme that can detect light from 0.32◦ and 177.6◦, from an extreme forward to the backscattering regime, involving 46 angles. Our setup was able to measure all six independent scattering matrix elements; however, we focused on measuring the scattering intensity and the linear depolarization ratio for different dust particles. Given the extremely small and large angles, the data obtained for our setup are plotted on both: versus scattering angle, θ linearly, and scattering wave vector, q or qR with R the radius of a particle, on a log-log scale, called θ and Q-space respectively. The Q- space analysis best represents the data at the extreme forward scattering regime; however, it compresses the data at the large scattering angles, θ , where useful data also reside. At large scattering angles, the scattered intensity is best viewed by θ-space analysis. We scattered the light from different aerosol particles viz; silicon dioxide (SiO2), alu- minum abrasive (Al2O3), a highly refractive molybdenum disulfide (MoS2), a highly ab- sorptive hematite particle (α−Fe2O3), arizona road dust and Soot particles. The measured scattered intensity was interpreted by applying both analysis methods. Light scattering for all particle types was compared to theoretical Mie scattering calculations using size distributions determined by an Aerodynamic Particle Sizer (APS 3321), an aerosol mea- suring instrument. The compared results between the experimentally measured data and Mie calculations showed a close agreement at the forward scattering regime and poorly at the side and backscattering regimes. Effects of the intensity-weighted size distribution were discussed. We applied Guinier analysis on light scattering measured data to compare light scattering inferred size to the intensity-weighted mean sizes for all shape particles. The light scattering sizes were consistent with the intensity-weighted mean sizes of reasonable accuracy for any shape and refractive index. This result has demonstrated the importance of intensity weighting of the size distribution in light scattering. We measured and studied the linear depolarization ratio for different dust particles. They all displayed a common pattern. The measured values were negligibly small at the forward scattering regime. They increased with increasing the scattering angle and reached a max- imum at the side scattering regime that generally droped off at the backscattering regime. The effects of particle asphericity, size, and refractive index on the linear depolarization ratio were investigated. We further investigate the light scattering from fractal soot and non-fractal hematite ag- gregates. The results showed an enhancement in the backscattering despite a large imaginary refractive index. We found that enhancement backscattering for the non-fractal aggregate is due to internal multiple scattering between the grains within the aggregate. In contrast, enhancement backscattering is yet to be understood for fractal soot aggregates. Further- more, the results presented in this work showed the sensitive of light backscattering with the change in particles’ shapes, sizes, and refractive indices and warn the experimentalist to use the backscattering measured data with great caution

A taste of empathy in the social science class

Teaching social science in upper primary has its own uniqueness since learners can understand changes in human society through the community around us, by close observations at homes, through newspapers, media etc. A teacher also gets similar experiences from community

Summer holidays as informal learning experience

Leisure of the summer holidays is so important because children can find a break from such pressures and get an opportunity to have some time of their own through the vacation

The lateral supramalleolar flap: a reliable option for lower leg and foot reconstruction

Background: The lateral supramalleolar flap is based on a perforator of the peroneal artery, emanating at approximately 5 cm above the lateral malleolus on the anterior aspect of lower third leg.Methods: Our technique of harvesting the supramalleolar flap is by using a fasciocutaneous pedicle and minimal perforator dissection. We have done 45 cases in the last 7 years and have got favourable results with this technique.Results: We have not had a single case of total flap necrosis of a supramalleolar flap in our experience over the last 7 years. We routinely perform this flap when the reverse sural flap territory is not available.Conclusions: The lateral supramalleolar flap is a useful flap for coverage of lower third leg, ankle and dorsal foot defects. If raised as described, the reliability of this flap is increased.