How different are shadows of compact objects with and without horizons?

In this work, we theoretically assume that a compact object (CO) can have a dark surface so that the CO is simplified to have no emissions and reflections. Considering that the radius of the surface can be located inside or outside the photon region, which is closely related to the shadow curve, we investigate if a CO without an event horizon could produce shadow structures similar to black holes and figure out how different of shadows of COs with and without horizons. In particular, by introducing the (possible) observational photon region, we analytically construct an exact correspondence between the shadow curves with the impact parameters of photons and find that there are indeed several differences for shadows of COs without horizons and black holes. More precisely, We found the shadow curve is still determined by the photon region when the radius of the surface is small enough to retain a whole photon region outside the shell. When only part of the photon region remains, the shadow curve is partially determined by the photon region, and the remaining portion of the shadow curve is partly controlled by the impact parameters of photons which has a turning point on the surface. When there's no photon region outside the surface, the shadow curve is totally controlled by the impact parameters of photons which has a turning point on the surface.Comment: 19 pages,5 figure

Multiple Key-value Strategy in Recommendation Systems Incorporating Large Language Model

Recommendation system (RS) plays significant roles in matching users information needs for Internet applications, and it usually utilizes the vanilla neural network as the backbone to handle embedding details. Recently, the large language model (LLM) has exhibited emergent abilities and achieved great breakthroughs both in the CV and NLP communities. Thus, it is logical to incorporate RS with LLM better, which has become an emerging research direction. Although some existing works have made their contributions to this issue, they mainly consider the single key situation (e.g. historical interactions), especially in sequential recommendation. The situation of multiple key-value data is simply neglected. This significant scenario is mainstream in real practical applications, where the information of users (e.g. age, occupation, etc) and items (e.g. title, category, etc) has more than one key. Therefore, we aim to implement sequential recommendations based on multiple key-value data by incorporating RS with LLM. In particular, we instruct tuning a prevalent open-source LLM (Llama 7B) in order to inject domain knowledge of RS into the pre-trained LLM. Since we adopt multiple key-value strategies, LLM is hard to learn well among these keys. Thus the general and innovative shuffle and mask strategies, as an innovative manner of data argument, are designed. To demonstrate the effectiveness of our approach, extensive experiments are conducted on the popular and suitable dataset MovieLens which contains multiple keys-value. The experimental results demonstrate that our approach can nicely and effectively complete this challenging issue.Comment: Accepted by CIKM2023 workshop at GenRec'2

A Project-based Quantification of BIM Benefits

In the construction industry, research is being carried out to look for feasible methods and technologies to cut down project costs and waste. Building Information Modelling (BIM) is certainly currently a promising technology/method that can achieve this. The output of the construction industry has a considerable scale; however, the concentration of the industry and the level of informatization are still not high. There is still a large gap in terms of productivity between the construction industry and other industries. Due to the lack of first-hand data regarding how much of an effect can be genuinely had by BIM in real cases, it is unrealistic for construction stakeholders to take the risk of widely adopting BIM. This paper focuses on the methodological quantification (through a case study approach) of BIM’s benefits in building construction resource management and real-time costs control, in contrast to traditional non-BIM technologies. Through the use of BIM technology for the dynamic querying and statistical analysis of construction schedules, engineering, resources and costs, the three implementations considered demonstrate how BIM can facilitate the comprehensive grasp of a project’s implementation and progress, identify and solve the contradictions and conflicts between construction resources and costs controls, reduce project over-spends and protect the supply of resources

Integrating Building Information Modelling and Firefly Algorithm to Optimize Tower Crane Layout

Abstract - Tower crane layout design and planning within construction site is a common construction technical issue and regarded as a complex combinatorial problem. To transport heavy materials, such as rebar, formwork, scaffolding, equipment and steel, tower cranes are needed and should be well located to reduce construction cost and improve safety management. Currently, practitioners in the industry are over-reliance on individual experience and subjective judgment during decision-making process. The purpose of this paper wants to develop a well-defined approach, which integrating Building Information Modelling (BIM) and firefly algorithm to come up with an optimal tower crane layout for construction projects. Firstly, BIM technology is utilized to automatically generate the quantity of materials which need to be transported. Then firefly algorithms are used to determine the locations of tower cranes, supply points and demand points according to transportation requirement, time and cost. Thirdly, the optimal tower crane layout scheme will be visualized by 4-Dimension (4D) BIM to verify its constructability and safety based on computer simulation and individual experience. Finally, a practical case is selected to evaluate the developed approach. In addition, some lessons learned and issues are highlighted that help direct future research and implementation. The optimization results of the example are very promising and it demonstrates the application value of the approach

Perbandingan Harga Energi dari Sumber Energi Baru Terbarukan dan Fosil

PERBANDINGAN HARGA ENERGI DARI SUMBER ENERGI BARU TERBARUKAN DAN FOSIL. Transportasi biaya rendah untuk orang dan barang sangat penting untuk kesejahteraan ekonomi bangsa. Hingga kini jika harga minyak naik, biaya transportasi otomatis akan mengikuti dan sebagian rakyat menderita akibat melambungnya harga makanan dan barang-barang lainnya. Hampir 100 persen kebutuhan energi transportasi negara Indonesia didukung oleh minyak. Sementara biaya di sektor energi terutama listrik, di negara maju yang juga berperan signifikan untuk mendukung transportasi, jauh lebih stabil dan dapat diprediksi. Kebutuhan energi yang begitu tinggi di sektor transportasi cenderung memaksa manusia untuk mengupayakan sumber dan sarana energi dalam bentuk lain seperti listrik atau hydrogen yang dapat menyamai atau melebihi kinerja bahan bakar minyak. Makalah ini bertujuan untuk menganalisis perbandingan keekonomian harga energi dari sumber EBT dan fosil untuk melihat sejauh mana peluang keekonomian beberapa jenis energi dapat memainkan peran signifikan di sektor transportasi dan dampak selanjutnya di dalam sistem energi. Metodologi yang digunakan adalah penelusuran pustaka dan perhitungan langsung pada bahan atau sumber energi terkait. Dari hasil analisis diperoleh bahwa akan semakin dibutuhkan peran energi nuklir dan energi tertentu lainnya sebagai sumber energi listrik menimbang aspek keekonomiannya yang relatif lebih baik