Evaluation of the vertical strenght of a 3000 tdw barge using the equivalent beam approach

For the preliminary design stage, the evaluation of vertical strength is mandatory for the preliminary scantling of the structure. This paper presents the evaluation of the vertical sectional efforts by equivalent beam approach, using the 3D-CAD lines plan of a 3000 tdw barge and mass diagram. For numerical analysis the own program P_QSW is used, for sagging and hogging wave condition, ship headings 0 and 45o, wave height max. 1.2 m. The vertical sectional efforts are compared with the maximum bending moment and shearing force prescribed by the classification societies for the 3000 tdw preliminary vertical strength assessment.

DEVELOPMENT OF LEARNING TRAJECTORY ON THE SET TOPIC FOR 7TH GRADE IN THE CONTEXT OF SEDEKAH LAUT TRADITION

Set is an important topic to be mastered by students because it influences the development of mathematics in daily life. However, many students still have difficulty learning the topic. Therefore, it is necessary to design a learning trajectory using the appropriate approach, context, and media. This research resulted in the learning development using Sedekah Laut context to create meaningful learning and increase students' understanding of sets. The method used in this study was design research proposed by Gravemeijer & Cobb with three stages: preliminary design, experimental design (pilot experiments and teaching experiments), and retrospective analysis. However, this article only presented the results from the Preliminary design stage. The participants involved in this study were 7th-grade students of SMP Negeri 6 Semarang. The resulting hypothetical learning trajectory consists of a series of learning processes: observing context videos to find the concepts of sets, non-sets, empty sets, universal sets, and Venn diagrams; explaining the properties of the set; defining set operations; and solving problems related to sets.

A Replicable Methodology to Evaluate Passive Façade Performance with SMA during the Architectural Design Process: A Case Study Application

Huge efforts have been made in recent decades to improve energy saving in the building sector, particularly focused on the role of façades. Among the explored viable solutions, climate-adaptive building shells [CABS] consider promising solutions to control solar radiation, both in terms of illuminance and heating levels, but are still piloting these solutions due to their complex designs and necessary costs. The present study aims to provide a speedy but reliable methodology to evaluate the potential impacts of adopting active/passive CABS systems during the preliminary design stage. The proposed methodology allows the evaluation and comparison, when multiple options are considered, of the effects of each solution in terms of the energy needs, thermal comfort and lighting, while reducing the required effort and time for an extensive analysis of the overall building level. This is based on the use of a “virtual test room” where different conditions and configurations can be explored. A case study in the city of Bologna is included for demonstration purposes. The achieved results support the decisions made regarding energy behavior (over/under heating), indoor comfort, lighting and energy at an early design stage.

Energy-Efficient Wireless Weight Sensor for Remote Beehive Monitoring

This paper proposes a new approach to the construction of an autonomous weight sensor for electronic beehive scales, constituting a crucial part in equipment used in the modern beekeeping economy. The main goal of this work is to demonstrate a methodology at the preliminary design stage leading to saving scarce energy resources necessary for the remote operation of a wireless network of beehives. The main findings of the work, achieved results, and identified threats for beekeeping scales operating in the real environment are also shown. The results presented in the article are based on actual data collected and recorded from several dozen beekeeping scales operating in the natural environment over a period of several years.

Near-Earth Asteroid Capture via Using Lunar Flyby plus Earth Aerobraking

Capturing Near-Earth Asteroids (NEAs) in the Earth-Moon system is a potential method of future space exploration and resource utilization. In order to make the captured NEA easily rendezvoused by spacecrafts, it is expected to capture the asteroid in a low-energy and low-inclination orbit. Lunar flyby and Earth aerobraking have been proved to be effective energy-saving methods in asteroid retrieval missions. Based on the Earth aerobraking capture strategy, if a lunar flyby process is performed before the asteroid enters the atmosphere, the thermal ablation of the asteroid in the atmosphere is expected to be alleviated. This paper proposes a lunar flyby plus Earth aerobraking method to capture an NEA. Using Geostationary Transfer Orbit (GTO) as the target orbit, the efficiency of three different capture strategies (direct capture strategy, Earth aerobraking capture strategy and lunar flyby plus Earth aerobraking capture strategy) are compared. Compared to the Earth aerobraking capture strategy, simulation results show that the main advantage of the lunar flyby plus Earth aerobraking capture strategy is that the mass loss ratio can be reduced (15 real asteroids are used as examples and mass loss ratio can be reduced by 0.98–3.39%). For example, for an asteroid with a diameter of 5 m, the mass is about 170.17 tons (with a density of 2.6g/cm3), reducing the mass loss ratio by 1% means that 1701.7 kg of the asteroid materials can be saved. Meanwhile, if the asteroid has a suitable phase for lunar flyby, while reducing the mass loss ratio, the fuel consumption can also be reduced. Furthermore, the conditions that do not require maneuvering between the lunar flyby and Earth aerobraking are preliminarily discussed. During the preliminary design stage of asteroid retrieval missions, compared with the Earth aerobraking capture strategy, lunar flyby plus Earth aerobraking capture strategy provides a potentially effective option for reducing the mass loss and the fuel consumption.

Didactical Tool for Wing Weight Estimation in a Preliminary Aircraft Design Stage

Aircraft preliminary design requires a lot of complex evaluations and assumptions related to design variables that are not completely known at a very initial stage. Didactical activity becomes unclear since students ask for precise values in the starting point. A tentative in providing a simple tool for wing weight estimation is presented for overcoming these common difficulties and explaining the following points: a) the intrinsic iterative nature of the preliminary design stage, b) provide useful and realistic calculation for the wing weight with very simple assumption not covered by cumbersome calculations and formulas. The purpose of the paper is to provide a didactic tool to facilitate the understanding of some steps in estimating wing weight at the preliminary design level. The problems of identifying the main variables for the initial estimation is dealt with and specifi aspects that are usually hidden by the complexity of the involved disciplines and by the usual calculation methods applied in structural design are pointed out. The procedure is addressed to highlight main steps in wing weight estimation for straight wing weight to highlight the main steps in estimating the wing weight for a general aviation straight wing aircraft at the preliminary design stage. The effect of the main variables on the wing weight variation is also presented confirming well-known results from literature and design manuals.

Didactical Tool for Wing Weight Estimation in a Preliminary Aircraft Design Stage

Aircraft preliminary design requires a lot of complex evaluations and assumptions related to design variables that are not completely known at a very initial stage. Didactical activity becomes unclear since students ask for precise values in the starting point. A tentative in providing a simple tool for wing weight estimation is presented devoted to overcome these common difficulties and clarifies the following points: a) the intrinsic iterative nature of the preliminary design stage, b) provide useful and realistic calculation for the wing weight with very simple assumption not covered by cumbersome calculations and formulas. The procedure is applied to the calculation of wing weight for a typical general aviation aircraft in the preliminary design stage. The effect of the main variables on the wing weight variation is also presented confirming well-known results from literature and design manuals.

Aerodynamic Characterization of Hypersonic Transportation Systems and Its Impact on Mission Analysis

This paper aims to provide technical insights on the aerodynamic characterization activities performed in the field of the H2020 STRATOFLY project, for the Mach 8 waverider reference configuration. Considering the complexity of the configuration to be analyzed at conceptual/preliminary design stage, a build-up approach has been adopted. The complexity of the aerodynamic model increases incrementally, from the clean external configuration up to the complete configuration, including propulsion systems elements and flight control surfaces. At each step, the aerodynamic analysis is complemented with detailed mission analysis, in which the different versions of the aerodynamic databases are used as input for the trajectory simulation. eventually, once the contribution to the aerodynamic characterization of flight control surfaces is evaluated, stability and trim analysis is carried out. The comparison of the results obtained through the different mission analysis campaigns clearly shows that the accuracy of aerodynamic characterization may determine the feasibility or unfeasibility of a mission concept.