THE IMPACT OF DESIGN CHANGES IN CONSTRUCTION PROJECTS ON THE COST CHARGED BY CONSULTANT OFFICES

In any construction project, a large number of modifications occur. The consequences of those modifications may result in additional costs due to the re-design of the project on each member of the project’s stakeholders. The financial impact of modifications during the construction phase of a project on consultant offices will be explored in this study. The aim of this study is to investigate the cost of the modifications and to examine the type of relationship between the time ‎spent on the design to accomplish the modifications and the amount of money earned in the return of the ‎extra work done. As a wrong estimation of the additional cost may lead to an atrocious financial ‎impact on the office and dramatic consequences. Professional interview method was used to collect data from four different Lebanese consultant offices. Eleven projects were selected in this study. These projects were categorized into three different groups based on the initial cost of the structural design. A regression model that can be used to forecast the cost of extra work for modifications based on the initial design cost was derived in this study. The outcome of this study will simplify the forecasting of cost of any modification in construction projects

THE LACK OF FIRE SAFETY KNOWLEDGE AND IMPLEMENTATION THE CASE OF HIGH-RISE BUILDINGS

High-rise buildings are growing rapidly in number around the world. They are becoming important landmarks that mark out certain geographical areas. The fires of high-rise building have many characters not found in traditional low-rise buildings, like the variety of blazing factors, ways of fire spreading, and difficulty of evacuation. Hence, the protection features of conventional fire methods are not sufficient in designing towers. The paper, at first, summarizes the characteristics of high-rise buildings and fires, the unique features of Tall Buildings and the special life safety requirements for the high-rise buildings. Consequently, the topic of fire and life safety codes implementation during the design and construction phases should be brought to the forefront into the building design process, in order to improve the skills of architectural engineers concerning the integration of safety and fire protection methods. Then, case studies have been selected from PETRONAS tower Malaysia, MARINA tower Beirut, and BURJ KHALIFA ,UAE; which are designed by various legislations. This shows that there is a direct link between design outcomes and the legislation of buildings

ALLOCATION SOLUTIONS FOR RECYCLED MUNICIPALWASTE AGGREGATES

Municipal waste presents major environmental and public health concerns. The disposal of municipalwaste has become a major worldwide environmental problem. Landfill sites are considered as environmentally questionable option and their capacity are decreasing rapidly. Nowadays, various processes have emerged to recycle the waste as synthetic fuel gas, heat source, polymers, fertilizers, and particulate solid residues. In this study, the possibility of recycling these particulate solids as aggregate in concrete was considered. The physical properties and size distribution of recycled aggregates were measured along with the effect of using these recycled aggregate on the compressivestrength of concrete. The resulting outcomes of these tests were compared with concrete sample prepared with conventional crushed stone as coarse aggregate and natural sand as fine aggregate materials. No doubt, recycled aggregates can be used as a replacement of natural course and fine aggregates, but there is need for further investigations about its effect on the concrete properties

The evolution of strategic timing in collective-risk dilemmas

In collective-risk dilemmas, a group needs to collaborate over time to avoid a catastrophic event. This gives rise to a coordination game with many equilibria, including equilibria where no one contributes, and thus no measures against the catastrophe are taken. In this game, the timing of contributions becomes a strategic variable that allows individuals to interact and influence one another. Herein, we use evolutionary game theory to study the impact of strategic timing on equilibrium selection. Depending on the risk of catastrophe, we identify three characteristic regimes. For low risks, defection is the only equilibrium, whereas high risks promote equilibria with sufficient contributions. Intermediate risks pose the biggest challenge for cooperation. In this risk regime, the option to interact over time is critical; if individuals can contribute over several rounds, then the group has a higher chance to succeed, and the expected welfare increases. This positive effect of timing is of particular importance in larger groups, where successful coordination becomes increasingly difficul

EMERGENCY VEHICLES ALLOCATION MODEL FOR URBAN CITY

The Emergency Medical Service (EMS) plays a vital role in any community. The accessibility, distribution, and utilization of the emergency health care services have a great impact on the effectiveness and the efficiency of the EMS. In this study, an algorithm has been devised to optimize choosing the appropriate station location, allocating the right number of emergency vehicles to a station, and directing the critical and non-critical patients to the most suitable hospitals. XPRESS-MP solver engine was used in this study to derive a deterministic mathematical model using mixed integer linear programming. This model is customized for Beirut city. The aim of the study is to design a system that ensures that an emergency vehicle should be available at the time of the incident and the travelling time required must be less than the standard travelling time. The outcome of the study optimizes the number and the location of the EMS stations as well as the number of emergency vehicles allocated to each station. In addition, it optimizes addressing and readdressing the patients to the most suitable hospitals taking into consideration deterioration of the patients’ health conditions while being driven to the hospital. Furthermore, the travel time presented in this study shows the shortest travel distance between any two zones

ALLOCATION SOLUTIONS FOR RECYCLED MUNICIPALWASTE AGGREGATES

Municipal waste presents major environmental and public health concerns. The disposal of municipalwaste has become a major worldwide environmental problem. Landfill sites are considered as environmentally questionable option and their capacity are decreasing rapidly. Nowadays, various processes have emerged to recycle the waste as synthetic fuel gas, heat source, polymers, fertilizers, and particulate solid residues. In this study, the possibility of recycling these particulate solids as aggregate in concrete was considered. The physical properties and size distribution of recycled aggregates were measured along with the effect of using these recycled aggregate on the compressivestrength of concrete. The resulting outcomes of these tests were compared with concrete sample prepared with conventional crushed stone as coarse aggregate and natural sand as fine aggregate materials. No doubt, recycled aggregates can be used as a replacement of natural course and fine aggregates, but there is need for further investigations about its effect on the concrete properties

OPTIMIZATION OF SUPERMARKET CHECKOUT COUNTERS USING INTEGRATED GREEDY ALGORITHM

Supermarkets worldwide are facing a service dilemma whether to increase or decrease their number of counters used at checkouts. A higher number of checkouts will undoubtedly reduce waiting time at checkout, a factor in improving customer satisfaction and service quality but this will come at a cost to the Supermarket. The work conducted in this paper will therefore focus on this tradeoff between improving the customer shopping experience versus the Supermarket Cost and profitability margins. It will do so by using an optimization algorithm that can help find the optimum number of checkouts and utilization of staff resources. The optimization algorithm uses discrete event simulation approach that applies arena integrated with Greedy algorithm, using real-life data The aim of this integration is to combine the strength of the simulation that optimize large set of feasible solutions, with the advantage of the greedy algorithm to reduce the design space of feature inputs, which would facilitate optimizing the process in the shortest time possible. The developed integrated greedy algorithm has proved successful in optimizing the staff resource efficiency as well as achieving the optimum number of checkouts

Density-aware NeRF Ensembles: Quantifying Predictive Uncertainty in Neural Radiance Fields

We show that ensembling effectively quantifies model uncertainty in Neural Radiance Fields (NeRFs) if a density-aware epistemic uncertainty term is considered. The naive ensembles investigated in prior work simply average rendered RGB images to quantify the model uncertainty caused by conflicting explanations of the observed scene. In contrast, we additionally consider the termination probabilities along individual rays to identify epistemic model uncertainty due to a lack of knowledge about the parts of a scene unobserved during training. We achieve new state-of-the-art performance across established uncertainty quantification benchmarks for NeRFs, outperforming methods that require complex changes to the NeRF architecture and training regime. We furthermore demonstrate that NeRF uncertainty can be utilised for next-best view selection and model refinement

ParticleNeRF: A Particle-Based Encoding for Online Neural Radiance Fields

While existing Neural Radiance Fields (NeRFs) for dynamic scenes are offline methods with an emphasis on visual fidelity, our paper addresses the online use case that prioritises real-time adaptability. We present ParticleNeRF, a new approach that dynamically adapts to changes in the scene geometry by learning an up-to-date representation online, every 200ms. ParticleNeRF achieves this using a novel particle-based parametric encoding. We couple features to particles in space and backpropagate the photometric reconstruction loss into the particles' position gradients, which are then interpreted as velocity vectors. Governed by a lightweight physics system to handle collisions, this lets the features move freely with the changing scene geometry. We demonstrate ParticleNeRF on various dynamic scenes containing translating, rotating, articulated, and deformable objects. ParticleNeRF is the first online dynamic NeRF and achieves fast adaptability with better visual fidelity than brute-force online InstantNGP and other baseline approaches on dynamic scenes with online constraints. Videos of our system can be found at our project website https://sites.google.com/view/particlenerf

ALKALI TREATMENT OF FAN PALM NATURAL FIBERS FOR USE IN FIBER REINFORCED CONCRETE

It is well known that the addition of fibers to concrete mix enhancesits performance. There are many types of fibers in the market, but forenvironmental protection purposes, the use of natural fibers rather thansynthetic fibers is highly recommended. However, natural fibers are affectedby the presence of Alkali environment of concrete; however, treating fiberswith chemical solution reduces the effect of Alkali attack and overcomes theweak bond between the fiber and the cement matrix by formation of a roughfiber surface. Alkali treatment is one of the most used methods for treatmentof natural fibers. In this study various Alkali treatment procedures on FanPalm fibers have been used to define the optimum procedure that enhancesthe durability of Fan Palm natural fiber in concrete without causing seriousdeterioration to the fiber itself. For that, an experimental program wasconducted to study the effect of different treatment procedures on the tensilestrength of fibers, modulus of elasticity, and the elongation of fibers at break.Thus, the treatment was applied at various concentrations of SodiumHydroxide solutions (1%, 2%, 4%, & 10%) and treatment durations (2 hrs , 8hrs, & 24 hrs ). From the tested fibers, the maximum tensile forces at breakand elongations were recorded. From the analysis of test results it wasconducted that using 4% sodium hydroxide concentration for 24 hours wasthe preferred treatment procedure for Fan Palm fibers