A Dynamic Flexible Partial-Adjustment Model of International Diffusion of the Internet

The paper introduces a dynamic, flexible partial-adjustment model and uses it to analyze the diffusion of Internet connectivity. It specifies and estimates desired levels of Internet diffusion and the speed at which countries achieve the target levels. The target levels and speed of adjustment are both country and time specific. Factors affecting Internet diffusion across countries are identified, and, using nonlinear least squares, the Gompertz growth model is generalized and estimated using data on Internet users for 59 countries observed over the years 1995 to 2002. The empirical results show that infrastructure variables such as personal computer ownership and telephone service increase the equilibrium level of internet diffusion. The speed of adjustment toward a target level decreases over time. Regarding model performance, the generalized dynamic Gompertz model that accounts for unobserved country heterogeneity effects outperforms other, simpler and static model specifications.technology diffusion; Internet; panel data; technology adoption; Gompertz model

Influence of the Reactant Temperature on Particle Entrained Laminar Methane-Air Premixed Flames

This study investigates the laminar burning velocity of premixed methane-air mixtures, having controlled supply of micron-sized (75-90 ¥ìm) coal dust and sand particles over a range of gas phase equivalence ratios (0.9-1.2), dust concentrations (0-250 g/m3) and reactant temperatures (297, 350, 400 K) using a novel Bunsen-burner type experimental design. The experimental results show that, the laminar burning velocity is enhanced by the increase in the reactant temperature, irrespective of the equivalence ratio of the mixture due to enhanced reaction rates. Addition of coal particles in fuel lean (ϕ \u3c 1) mixtures increases the laminar burning velocity initially up to a certain coal dust concentration, but after that, the trend is altered; either it remains constant or shows a decreasing trend. The dust concentration value, which produces the initial or local maximum, increases with increase in reactant temperature. In other words, the reactant temperature plays a significant role in the trend of increase in laminar burning velocity with dust addition. For ϕ \u3e 1, at a given reactant temperature, a linear decay of burning velocity with dust addition is observed. When a combustible dust particle interacts with the flame zone, it extracts energy from the flame (heat sink effect) and releases volatiles, thereby changing the local equivalence ratio around the flame zone. Both, increase in the equivalence ratio and the heat sink effect, are influenced by the reactant temperature. A mathematical model including these effects is developed and the model predictions are compared with the experimental results. The results are in a good agreement for fuel lean and stoichiometric mixtures; whereas the model is found to under predict results for fuel rich cases, and needs further improvements

Hidden structure revealed

This MFA Thesis is based on the aesthetic philosophy that all forms and structures are essentially made from cubes. This premise has inspired and shaped my explorations over the last two years of graduate study. Shape and meaning of ‘cubes’ can be simplified to the smallest molecular units of objects. The geometric forms I construct reflect this. I have mostly created vessel-oriented forms, but now I find that I can also make sculptures that reflect the same point of view. The shape of the earth is a theme and inspiration for this thesis project. Craters, which show their inner side, are expressive. Landscapes, which are usually more organic than geometric or symmetric, correlated to the outer shape of my work. This outer shape contains craters. The geometry expressed inside the craters contrasts with the spontaneity of the outside shape. The use of contrasting colors is also an important factor in my work. An example is the use of gold on the geometric surface because of its metaphorical meaning of preciousness. In terms of material and technique, I’d like to keep every possibility open, from cone 10 to cold finishing, from slip casting to hand building and wheel throwing. That way, the fabrication of each individual piece is based on its essential characteristics. This concept will also add visual variety across the entire collection of work

5th Grade Space-Enriched Science Curriculum Unit Development Project

This project was to develop a six-week long 5th grade hands-on curriculum unit. It brought aerospace back into the curriculum using a lunar base theme. This project was sponsored by the AIAA New England. The initiative was hosted by Elm Park Elementary school in Worcester, MA, in the classroom of a science-oriented teacher. There, we tested ideas that would become 7 science-concept review stations at an AIAA NE outreach event (at WPI), for 375 fifth graders from 7 schools, called Fifth Grade MCAS Review - on the Moon . This event evolved out of a request for a field trip. Part of the project was to do a cost-benefit analysis of bringing in a guest speaker, going on a field trip, or creating your own event. The Worcester Public Schools liked our event the best, and want it repeated

S-CLIP: Semi-supervised Vision-Language Learning using Few Specialist Captions

Vision-language models, such as contrastive language-image pre-training (CLIP), have demonstrated impressive results in natural image domains. However, these models often struggle when applied to specialized domains like remote sensing, and adapting to such domains is challenging due to the limited number of image-text pairs available for training. To address this, we propose S-CLIP, a semi-supervised learning method for training CLIP that utilizes additional unpaired images. S-CLIP employs two pseudo-labeling strategies specifically designed for contrastive learning and the language modality. The caption-level pseudo-label is given by a combination of captions of paired images, obtained by solving an optimal transport problem between unpaired and paired images. The keyword-level pseudo-label is given by a keyword in the caption of the nearest paired image, trained through partial label learning that assumes a candidate set of labels for supervision instead of the exact one. By combining these objectives, S-CLIP significantly enhances the training of CLIP using only a few image-text pairs, as demonstrated in various specialist domains, including remote sensing, fashion, scientific figures, and comics. For instance, S-CLIP improves CLIP by 10% for zero-shot classification and 4% for image-text retrieval on the remote sensing benchmark, matching the performance of supervised CLIP while using three times fewer image-text pairs.Comment: NeurIPS 202

A novel method for crystalline silicon solar cells with low contact resistance and antireflection coating by an oxidized Mg layer

One of the key issues in the solar industry is lowering dopant concentration of emitter for high-efficiency crystalline solar cells. However, it is well known that a low surface concentration of dopants results in poor contact formation between the front Ag electrode and the n-layer of Si. In this paper, an evaporated Mg layer is used to reduce series resistance of c-Si solar cells. A layer of Mg metal is deposited on a lightly doped n-type Si emitter by evaporation. Ag electrode is screen printed to collect the generated electrons. Small work function difference between Mg and n-type silicon reduces the contact resistance. During a co-firing process, Mg is oxidized, and the oxidized layer serves as an antireflection layer. The measurement of an Ag/Mg/n-Si solar cell shows that Voc, Jsc, FF, and efficiency are 602 mV, 36.9 mA/cm2, 80.1%, and 17.75%, respectively. It can be applied to the manufacturing of low-cost, simple, and high-efficiency solar cells