Search

The common building material utilized throughout the ancient world was lime. However, the development of cement quelled its prominence. Although cement was proven to have numerous uses in the construction business, it was determined to be harmful when used as a repair material, especially for historic buildings. The main cause is that the strength and service life related properties of cement are incompatible with the substrate (ancient lime) and masonry units. Nano-silica (NS) is a well-known mineral admixture hence it is taken for analysis. The characterization of NS in lime mortar is studied. From the different historic sites, the mortar's physical properties are determined. After adding 2% NS, in the fly ash concrete the setting time reduced to 90 minutes and predominant, it is reasonable to take for granted that the carbonation reaction plays a key role in the mortar's strength. In this study identified as calcite is primarily composed of fly ash were less resistant to salt crystallization than mortars made of lime that had been substituted with GGBS. When NS was added to cement paste it increases flexural and compressive strength. In place of fly ash, GGBS produced a larger rate of decrease in the water absorption coefficient through capillarity, which is comparable to porosity. These mortars were capable of being used as restoration materials for historic buildings since they closely resembled physical characteristics of ancient mortars. [ABSTRACT FROM AUTHOR]

As an alternative to conventional steel or concrete building, steel-concrete composite construction has acquired great appeal worldwide. In comparison to many other economically emerging countries, India uses a slightly lower volume of steel in the construction sector. The composite buildings will contribute a significant value in the construction of tall buildings. These structures offer less dead load and are more cost-effective than conventional structures. An earthquake can occasionally leave damage that is irreparable and is highly unanticipated. it is impossible to stop natural tragedies, but it is still feasible to lessen its effects. Therefore, only faithful design can ensure all behavioural activities can control seismic impact on a structure's behaviour. One of the novel methods that can be combined for improved outcomes is base isolation and fluid viscous damper taken into account during the study of these buildings. These retrofitting helps the structures to dissipate the energies and lessen the earthquake impacts. [ABSTRACT FROM AUTHOR]

Based on kinematics theory, this paper proposes a computational tool that can rapidly assess the damage mechanism of aggregates in masonry structures. In this approach, some pre-assigned local mechanisms are assessed on a three-dimensional (3D) model of the whole aggregate, on which the shape of the involved macro-blocks is directly modelled. The method uses the principle of virtual work to calculate the horizontal load multiplier, judge the local failure mechanism, and carry out the reinforcement design. The method realizes coding in AutoLIS language function, uses AutoCAD software to model, and then realizes operation. The case analysed in the paper is an example from the 17 masonry aggregates located in the historical centre of Arsita. This aggregate is referred to as "Il Torrione". [ABSTRACT FROM AUTHOR]

Over the years, various surveying techniques have been employed to gather spatial data regarding ancient monuments, archaeological sites or historical buildings in order to preserve and protect cultural heritage. Initially, traditional methods were used, and even now, they continue to be appropriate for acquiring precise two-dimensional data. This process involves gathering information by measuring each detail as a set of points, each point being assessed separately. However, this approach can be quite time-consuming, especially when dealing with highly complex architectural elements, such as ornaments, numerous details, ornate facades, intricate stonework, and various architectural elements often present in historical buildings. The rapid advancement of technology in recent years, coupled with the demand for obtaining three-dimensional data of an object, has led to the development of a new data acquisition technique using laser waves, known as laser scanning. The following paper presents the application of terrestrial laser scanner (TLS) technology for the examination and assessment of historical buildings and cultural heritage sites. This scanner enables the creation of a realistic 3D geometric model of a building without the need for direct physical interaction with the structure. By using this groundbreaking technique, the comprehensive analysis and documentation of each structural and non-structural detail without causing harm to the edifice is possible. This approach yields a rich dataset of information, facilitating the preservation of architectural features and ensuring precision in the event of any future restoration needs. [ABSTRACT FROM AUTHOR]

While dealing with existing steel constructions, an high level of variability is encountered with reference to structural conception and typology of load-carrying systems. Furthermore, such structures often prove to be non-compliant with current codes, thus showing crucial structural shortages in many cases. Within this framework, an existing non-conforming six-storey steel building is in this article as a case study. The selected construction features both Moment Resisting Frames (MRFs) and Concentrically Braced Frames (CBFs) along its two main directions in plan. The seismic response of the selected structure was assessed in compliance with Italian and European standards, resulting in an inadequate performance and insufficient capacity. Hence, a global seismic refurbishment was conceived and numerically checked. Finally, results for the upgraded structure are compared to the performance of the as-built configuration. [ABSTRACT FROM AUTHOR]

The use of exoskeletons, intended as additive structures applied in a widespread way externally to the building to be protected, constitutes a valid alternative to common intervention techniques for the seismic retrofit of existing buildings. Among many typological solutions present in the literature, in the present work, the orthogonal 2D steel exoskeletons (called EXO 2D_λ) have been analysed in detail. These systems, made as truss shear walls placed orthogonally to the facade of the building, can be effectively used for the strengthening of low-mid-rise buildings. In the present work, after a thorough state-of-the-art and a critical analysis of recent realizations, a kit-constructive system, suitable for prefabrication, was conceived. [ABSTRACT FROM AUTHOR]

Non-structural systems represent the majority of the loss exposure of buildings to earthquakes. Moreover, with respect to the strategic building a critical issue, related to the failure of these systems, is the loss of the operability of the buildings. Within this framework, the evaluation of the seismic performance of light-weight suspended ceiling is the object of this work. Due to the lack of numerical simulation tools, the suspended ceiling's seismic behaviour can not be properly analysed and predicted. For this reason, an experimental characterization of the system is required. A review of the tests performed in previous research projects was presented. Finally, an innovative experimental characterization, performed by using a universal testing machine, to evaluate the capacity of a bracing system for ceilings under two different directions of the horizontal seismic action is presented. [ABSTRACT FROM AUTHOR]

A historic school building was recently retrofitted. Due to its high architectural quality, the building is listed as National Architectural Patrimony, and therefore the rehabilitation process has met very challenging requirements regarding its conservation to maintain the original layout. In view of its age, the building is done with thick stone walls which help energy conservation and enhance thermal inertia. Its primitive architecture enables natural lighting, increases solar radiation gains, and favors natural ventilation, assuring, consequently, an improved energy efficiency. The implemented rehabilitation actions tried to preserve the original architecture and the building restorations were designed to conserve as much as possible the ancient distinctive architectural style. Given the imposed constraints, matters like Indoor Air Quality (IAQ) and thermal comfort in rooms and offices for administration and staff were not met. The current situation has resulted in justifiable complaints from the building users, reporting poor rooms IAQ due to a lack of air renovation. Because of the impossibility to install mechanical ventilation ducts, the building rooms are operated through natural ventilation, which makes the adoption of constant air flow regimes difficult to implement. To evaluate the problem and promote measures to deal with it, an experimental campaign to assess IAQ and building thermal comfort was implemented during the Winter of 2022. In the framework of the campaign, two identical rooms with similar occupancy, size, volume, building typology, heating regime, and with the same equipment installed, were measured in situ for 3 months, by monitoring continuously the following variables: indoor radon concentration, air temperature and relative humidity, under distinct regimes of ventilation. By using statistical analysis of the experimental data, the results show, as expected, that the room with a permanent air renovation has an improved IAQ than the other monitored room, operated with a restricted ventilation schedule, without jeopardizing the energy efficiency. Based on the results, natural ventilation in a steady state mode is the key to balancing IAQ and energy efficiency. [ABSTRACT FROM AUTHOR]

This paper presents the evaluation of the fracture test of high-strength structural (HSS) steel grades S460 using a finite element (FEM) numerical model. Steels with better strength characteristics may exhibit different stress-strain diagram behavior and therefore material models need to be adequately prepared. The numerical model, which accurately simulates the experiments, was prepared using known information from tensile testing of high-strength steel. The aim is to determine the material parameters with high accuracy using inverse analysis so that complex numerical models of building structures such as steel halls and bridges can be prepared. The paper contains results from an experimental investigation compared with results from a numerical model of a tensile fracture test. Due to the good agreement, the derived material parameters can be applied in future research on high-strength structural steel in the construction industry. [ABSTRACT FROM AUTHOR]

The purpose of this study was to analyze the building energy conservation through visual comfort based on the intensity of lighting penetrating in the room. The building of Faculty of Sport Sciences, Universitas Negeri Malang (UM) was selected as a case study. The analysis was conducted by using DIALux Evo simulation to investigate the natural lighting performance. The input variables are floor plan, location, longitude and latitude, time zone, weather conditions, observation time, and simulation date. The results showed that: 1) Visual comfort in the classroom is influenced by room size, floor elevation of each room, window type, window orientation, and building materials, 2) The intensity of natural lighting can effectively provide visual comfort with the north and south orientation of the building at clear and overcast sky conditions that occurs on March 21 and average sky on September 23, 3) The intensity of natural lighting compared to SNI 03-6197-2000 is classified as comfortable category, which is 250 lux. [ABSTRACT FROM AUTHOR]

The importance of effective leadership skills for project managers cannot be overstated, especially in the pre-construction phase of sustainable building projects where they often face challenges. Stakeholders from diverse fields of study may present communication hurdles, making it imperative for project managers to sharpen their leadership skills. Given this pressing need, the study aims to explore the feasibility of a model that enhances the leadership abilities of project managers during the planning stages of environmentally responsible building projects. The research involved a review of existing sustainable construction maturity models and project managers' sustainable construction leadership skills. Additionally, a questionnaire was distributed to experienced project managers who have worked on sustainable building projects to identify critical leadership abilities required in the pre-construction phase and areas that need improvement. The resulting model is intended to aid project managers in enhancing their leadership skills before the construction phase of green buildings, thereby ensuring efficient and effective completion of sustainable construction projects. [ABSTRACT FROM AUTHOR]

Power quality monitoring has an increasing role in the deregulated electricity supply market. Industrial and commercial customers are increasingly getting affected by poor power quality problems. A web based, near real time power quality monitoring system is necessary to provide such information, both locally and on Nationwide basis to customers. This paper aims to dive into the development of a web-based power quality monitoring system for commercial building. The power quality web-based system implemented using Representational State Transfer Application Programming Interface (RESTful API) method as a web application. It also coordinates with a K-Nearest Neighbours machine learning model for classifying the power quality. In this project, the machine learning model managed to achieve an accuracy of 0.8125 over 1 which defines a good performance of the algorithm [ABSTRACT FROM AUTHOR]

The 2019 Light of Internet Expo main exhibition hall in Wuzhen, China has an innovative roof system combining beam strings, multi-span suspended beams and redundant wind-resisting cables, covering an area of 90 m × 211 m. The suspended 200 mm deep beams form an undulating roof of 35.5 m to 48 m in span length. The novel design, which efficiently combines architectural aesthetics and structural force flow, needed to be completed and built in just 7 months for the exhibition. This paper focuses on structural design issues such as form finding, shape optimisation and structural analysis. [ABSTRACT FROM AUTHOR]

The ever-increasing amount of data that is produced by modern scientific facilities like EuXFEL or LHC puts high pressure on the data management infrastructure at the laboratories. This includes poorly shareable resources of archival storage, typically, tape libraries. To achieve maximal efficiency of the available tape resources, a deep integration between hardware and software components is required. The CERN Tape Archive (CTA) is an open-source storage management system developed by CERN to manage LHC experiment data on tape. Although today CTA's primary target is CERN Tier-0, the data management group at DESY considers the CTA as a main alternative to commercial HSM systems. dCache has an extensible tape interface that allows connectivity to almost any tape system. Together with the CERN Tape Archive developers, the storage team at DESY is working on seamless integration of CTA into dCache. [ABSTRACT FROM AUTHOR]

An office building is designed to accommodate the activities of a company. Every office building must have a strong, rigid, and stable structure in carrying the load such that it can be used according to its function. Regular inspections of the reliability of existing office buildings must be carried out, especially if an update of the building codes has been introduced. In this study, a structural evaluation of an office building in Riau province, Indonesia was carried out based on the current Indonesian building standards. The structural analysis considering all the working loads on the building includes the dead, live, wall, and earthquake loads. For earthquake loading, a dynamic earthquake load with the Spectrum Response using SNI 1726:2019 was used in this analysis. This building was modeled and analyzed using the ETABS v.16 software. The evaluation of the structural capacity of the building was carried out on columns and beams. The capacity of the column was evaluated from a column interaction diagram (P-M diagram) and the shear capacity of the column, while the flexural and shear capacities of the beams were analyzed using Indonesia Standard SNI 2847:2019. The results of the analysis show that the building does not have sufficient capacity, especially on the second and third-floor beams. Therefore, it is necessary to retrofit the weak beams of the building. In this study, the retrofitting method of the beams was designed using Fiber Reinforced Polymer (FRP), a fiber material that is glued to the bottom beams by a matrix substance, such as epoxy or polyester. The finding of the research is the capacity of the retrofitted building structure has increased, which is capable to resist the working loads. [ABSTRACT FROM AUTHOR]

There are three concepts in the design of earthquake-resistant buildings: the service design method, the ultimate design method, and the performance-based design method. These three methods have advantages and disadvantages to the expected structural response design. In this paper, the design concept used is a performance-based method in which the structure is conditioned in a plastic state. This method is known as Performance Based Plastic Design. This design concept uses target drift and yield mechanism as its performance criteria. The modeling is for a 10-story reinforced concrete structure that functions as an office building. This building has a risk category II and a Building Priority Factor I. In the design step carried out on this building, checking for irregularities in the vertical and horizontal structures, the period of the structure, and the participation of the structure's mass have met the requirements for analyzing the structure's performance. The displacement target for the structure is still in an Immediate Occupancy condition. The response spectra used to see the structure's performance is using data from the city of Padang in the 2019 Indonesia Earthquake map. In the x direction with a displacement of 0.76% of the structure height and immediate occupancy (IO) in the y direction with a displacement of 0.58% of the structure height. So that the structure is concluded to be safe during an earthquake. [ABSTRACT FROM AUTHOR]

This paper presents the simplified method for evaluating the seismic performance of existing reinforced concrete (RC) buildings following The Japan Building Disaster Prevention Association standard. In this method, the seismic performance of RC buildings was described in lateral strength and ductility indexes of vertical members such as columns, short columns, and masonry walls. The simplified method was applied to assess the seismic performance of an existing building that survived the September 2009 West Sumatra earthquake. The evaluated building was a three-story RC building that used brick masonry walls as the infill. The shear stress of the brick infill was obtained based on the test results on the RC frame with brick infill under static lateral load. The analysis reveals the seismic performance of the building as the reason that the building could survive the earthquake. [ABSTRACT FROM AUTHOR]

The need for buildings to support the population's economy continues to grow, especially in big cities. On the other hand, the construction sector consumes 36% of the world's energy and accounts for 39% of all greenhouse gas emissions, such as CO2, in the world generated using fossil fuel electrical energy in buildings. In addition, the duration of activity of building occupants in the room can also affect the health of its occupants in the long term. This phenomenon is called sick building syndrome. Greenship, EDGE, and WELL standards which focus on environmental sustainability and the health of building occupants were introduced to solve these problems. However, to achieve this goal, the complexity of building design may increase. Building Information Modeling (BIM) can help unravel the complexities of design based on each of these three standards to their assessment. In the future, it is hoped that there will be more building professionals that prioritize the construction of buildings with Greenship, EDGE, and WELL standards in Indonesia. Therefore, this study focuses on the readiness of utilizing BIM in designing healthy-green buildings. This study uses a quantitative approach using questionnaire. Questionnaires were distributed to respondents with backgrounds as architects, contractors, or green building consultants. This study shows that the respondents are quite sure that BIM can facilitate the flow of information and communication of team members in the building design to the construction phase. However, when measuring the readiness of BIM technology to design, build, to simulate the operation of buildings that have high complexity such as healthy green building, the general consensus of the respondents is neutral with a slight tendency towards optimism on the BIM technology readiness. Respondents feel confident that BIM is best equipped to achieve Greenship standard design requirements. As for the other two standards, i.e., EDGE and WELL the respondents tend to be neutral. [ABSTRACT FROM AUTHOR]

A silo building is a storage area that serves to store granular materials. The Teluk Bayur Cement Silo Building is one of the industrial buildings at PT Semen Padang which function as a storage place for bulk cement before distributing it to other places. The Teluk Bayur Cement Silo Structure was built in 1996 using a prestressed concrete wall without any structural column. The building was designed by PT Partono Fondas using previous Indonesian building standards: SKBI-1.3.53.1987, SKSNI-T-15-1991-03, and PPTGIUG 1983. The Silo had 150 mm thickness at the roof plate, 400 mm thickness at the upper wall, 600 mm thickness at the cone wall, and 1000 mm thickness at the bottom wall with the section of the ring beam was 1000 x 1000 mm. In this building, the yield strength of steel (fy) were 240 MPa and 400 MPa for plain and deformed reinforcements, respectively, while the compressive strength of the concrete (fc') was 36.4 MPa, which was obtained from the hammer test results. Due to the change in Indonesian Building Standards, a structural analysis should be carried out to check the silo capacity in resisting the working loads. In this study, the current building standards including SNI 1727:2020, SNI 1726:2019, and SNI 7833:2012 were used in analyzing the silo building using the commercial software. SAP2000. The loads acting on the silo include dead, live, stored materials, earthquake, and wind loads. The structural analysis was carried out to determine the structural responses of the silo building such as the natural period of the structure, the prestressed force and losses in prestress, the plate deflection due to prestressed force, the prestress strength of radial moments, and silo deviation. The silo prestresses wall capacity was also calculated including wall tension control and reinforcing steel analysis. The result of the analysis shows that all the structure responses meet the permit limit requirements according to the Current Indonesian Standards Building. The finding of the research is that PT Semen Padang's Teluk Bayur Cement Silo still strong enough capacity to withstand the working load based on the current Indonesian Building Standards. [ABSTRACT FROM AUTHOR]

The hydrodynamic problems could be solved by assisting the computational fluid dynamics software, paid or based on open-source software. An open-source CFD software, OpenFOAM, is currently at the forefront of solving fluid-related problems, competing with paid CFD software, such as ANSYS Fluent, FLOW-3D, Autodesk CFD, or PHONICS. This study aims to show how OpenFOAM solves one of the fundamental hydrodynamic problems: water flow around a cylindrical obstacle. OpenFOAM's ability to solve turbulence problems at a boundary is determined by observing the flow pattern behind a cylindrical obstacle based on velocity profiles and streamlines. Meanwhile, OpenFOAM's ability to generate the resistance of an obstacle to fluid flow is determined by calculating the drag coefficient based on nine variations of the Reynolds number (Re). 2D flow simulations have been built with OpenFOAM using a CFD approach. OpenFOAM solves the Navier-Stokes equation for incompressible flow by applying the Finite Volume Method. A Turbulent Large Eddy Simulation (LES) k-equation model was chosen to overcome the turbulence. The water velocity field around a fixed diameter cylinder has been calculated using OpenFOAM based on the variation of Re from Re=0.1 (laminar flow) to Re=107 (turbulent flow). The velocity profile of the water behind the cylinder has been compared with the theory and shows a good agreement between the numerical and theoretical results. The streamlines pattern has similarities to the scientific literature. Finally, the drag coefficient (CD) is calculated based on the velocity field generated from the OpenFOAM calculations. The values of CD have followed the drag coefficient diagram of the scientific literature. The comparison test shows that OpenFOAM performs well in solving the problems of water flow through a cylindrical obstacle. The open-source CFD software OpenFOAM could be used as an alternative low-cost option to support studies related to hydrodynamics, such as aerodynamic studies, bridge pier structure design, wind and water turbine studies, and offshore/onshore foundation structure design, and breakwater design. [ABSTRACT FROM AUTHOR]

The main causes of duration deviation in school construction projects can be diagnosed with great success using root cause analysis approaches. To identify "the root cause" of a problem or non-conformance, a procedure called root cause analysis is performed. It eliminates or reduces the root cause and prevents the problem from recurring. Ishikawa diagrams, Pareto diagrams, and the Five Whys methodology are just a few of the root cause analysis methods that have emerged from the literature as broad methods for locating root causes. This study diagnosed thirty-three causes of duration deviation in school building projects in Iraq, which they divided into six groups (Contracting Documents, Contractor, Owner, Project Environment, Resident Engineer's Office, and External Factors). According to a Pareto analysis, eight factors out of thirty-three causes are responsible for 80% of the problem's duration deviation; these thirty-three causes had been filtered by a 5-Why analysis; this analysis concluded that the Inaccuracy of designs and drawing is a root cause for contracting documents group, while The project manager's inexperience and the poor efficiency of the contractors to which the contract was transmitted is a root cause for contractor group, Late payment of financial benefits by the owner is a root cause for owner group, Poor engineering awareness of the importance of time management in implementing engineers is a root cause for project environment group, Poor human resource efficiency of Resident Engineer Office is a root cause for resident engineer's office group, Financial and administrative corruption. It is a root cause for the external factors group. The 5-Whys study's final finding indicated that the root cause for duration deviation of school building projects is the poor engineering awareness of the importance of time management in implementing engineers. [ABSTRACT FROM AUTHOR]

In this modern era, Automated machines are about to migrate from factories and manufacturing industries to the building and construction industries as a result of rapid technological advances which enables them to perform complex task. Construction industry is facing issues like decling profit, low work productivity in construction, a high mishap rate, low quality, deficient control of building site, etc. In order to solve these issues Automation and Robotics is presented.A quantitative approach was done to collect data by case studies. The data is analysed to investigate various aspects of using automation like quality, cost, time, safety and productivity. The results showed that using automation in construction has positive impact in reducing cost, saving time, improving quality and increasing the productivity. [ABSTRACT FROM AUTHOR]

This work presents the use of an experimental coupled cross flow heat exchanger and underground water system to evaluate the use of this system for cooling animal farms under industrial conditions. The experiments were performed between 4 April and 12 June 2020, during the summer. The water flow rate in the test section was regulated between 10 to 15 litres per minute, while the air velocity varied from 4.5 to 10.5 m/s. The results indicate that the system can be used in areas such as Karbala city in Iraq for the cooling of farm buildings. During the test period, the maximum heat transferred to the ground was approximately 0.9 kW, with a mass flow rate of 0.16 kg/s. The maximum average temperature difference between the inlet water and ambient temperature was approximately 15 °C, while the air temperature inside the modular room decreased by about 12 °C. According to these results, direct ground cooling is a suitable method for the cost-effective cooling of buildings by circulating cold water through a heat exchanger. [ABSTRACT FROM AUTHOR]

According to World Health Organization (WHO), 60% of related factors to individual health and quality of life are correlated to lifestyle. Millions of people follow an unhealthy lifestyle which include bad food habits, physical inactivity, wrong body posture, and disturbed biological clock which directly contributes to lifestyle diseases. History has shown that environmental design can play a vital role in improving public health. Today, architects, urban designers, and planners can collaborate to address one of the most urgent and widespread epidemics of our time which are obesity and its related diseases. Hence, just as design professionals are increasingly embracing green building as an objective for environmental sustainability, they should thoroughly consider the potential effects of their designs on public health and well-being. Active Design is one of the approach that must been taken by the architecture field. It is an idea to design cities and buildings for Eco-sustenance that in turn can encourage people to get more exercise. This is not about encouraging us to go to the gym and working out more, but instead, it's about giving citizens more of a workout through how we interact with our environment on a daily basis. There are a few countries that have been publishing their own Active Design Guidelines in promoting the use of this approach on the building design. However, the active design guidelines are not yet publish in Asia, but the active design approach has been implemented and adapted in the building design whether in a direct or indirect manner. The purpose of this study is to examine, evaluate and review the building layout design in Malaysian Architecture in relation with the active design sustainable approach based on the literature and guidelines which can influence physical activities and health among Malaysian. Three selected building from Malaysia have been selected and analyzed through qualitative and quantitative method. The finding of the research would provide deeper understanding of the necessary parameters and factors that are needed to be considered in implementing the active sustainable design approach in Malaysia. [ABSTRACT FROM AUTHOR]

Present days' advances in the development of environmentally friendly passenger airplanes led to the creation of novel concepts such as the distributed electric and hybrid propulsion. In this direction of developments a not so radical concept is proposed of a complimentary electric fan propulsion system that is fully retracted in the wing during cruise, produces lift and thrust during takeoff and produces mainly lift during approach and landing phases of the flight. This study is aimed at preliminary evaluation of the 2D aerodynamic characteristics of the airfoil of such a system. The study is conducted using CFD software ANSYS Fluent. As a reference a 2D CFD model of the standard midspan airfoil of B737-300 aircraft is used. The reference model is validated with XFOIL. Landing and takeoff configurations are modeled based on the validated clean airfoil. In order to find the most effective fan position, two variants are investigated. The first one uses a ducted fan mounted on the top rear section of the airfoil. The other model features an "immersed" fan, where the fore flap is replaced by the electric ducted fan. Both configurations show a tendency to increase the overall lift and not only decrease drag but also produce thrust for operational angles of attack. Despite the similar results, the "immersed" fan produces slightly lower drag, which gives it the upper hand when it comes to takeoff. However, to make a confident statement, additional 3D studies would be needed. [ABSTRACT FROM AUTHOR]

Earthquakes are vibrations from the bowels of the earth that propagate to the surface caused by a sudden release of energy from within. Tectonic earthquakes are one of the most common types of earthquakes. The larger the Richter scale generated by the earthquake, the impact will result in both immaterial and material losses. Utilization of hardware and software in the field of technology as an effort to anticipate the impact caused by the earthquake. The system design can be done by utilizing a vibration detector against shocks that occur namely the sw-420 sensor, alarm to issue a warning sound by using the buzzer and Arduino as the main controller of the program. The earthquake detector is made to work when the SW-420 sensor gets a shock at 5 seconds that occurs repeatedly from 1 to 5 seconds. [ABSTRACT FROM AUTHOR]

The purpose of this research was to product Student Worksheet (LKPD) based on Contextual Teaching and Learning on the topic of vibrations and waves that have valid criteria so that it can be used in learning activities for junior high school students to build their observation skills. This development research uses the ADDIE model (Analysis, Design, Development, Implementation, and Evaluation). The instruments used in this study include validation sheets (materials and teaching materials experts) and the Observation Skills Assessment Rubric. The implementation stage is carried out in junior high schools in the Belitang Mulya sub-district. The results of this LKDP development research were obtained; 1) Valid with a score of 4.59 (material expert) and 3.09 (teaching material expert), 2) Valid with a score of 4.09 on a small-scale trial, 3) The implementation results obtained an average that students' observation skills were developed by 89.56% consisting of preparation of tools and materials, maximum use of senses, writing down relevant facts, drawing conclusions. Thus, it can be concluded that the CTL-based worksheets on the topic of vibrations and waves that were developed meet the valid criteria to be used for learning for junior high school students and can be used to build students' observation skills [ABSTRACT FROM AUTHOR]