Heavy Blimp-Based Simulation Research of Integral Tower Technology

The paper describes two minimum-cost, self-erecting, platform designs and one caisson structure design that can be installed in Cook Inlet, Alaska without the need for heavy lifting equipment. The Cook Inlet environment is characterized by thirty-foot tides and during the winter months by fast moving ice floes. The area is remote from other offshore operating areas and there is no heavy lifting equipment. One of the designs has been built and platform Osprey was installed in Cook Inlet in 2000. The paper will describe how it was designed, constructed and installed. A, second, different design concept allows platform installation in deeper water, again without the need for heavy lifting equipment. The third design concept is an outrigger caisson design that can be installed with a jack-up drilling unit. It would have application as a satellite platform structure. Use of these minimum-cost platform and caisson designs would enable development of marginal fields in Cook Inlet that heretofore could not be developed because the high cost of mobilizing and demobilizing heavy lifting equipment to and from Cook Inlet would make development uneconomic.

The paper describes the design, fabrication and installation of a novel self-erecting platform in Cook Inlet, Alaska. The platform project was completed by Forest Oil Corporation at a fraction of the cost of a conventional platform, thereby allowing exploration and subsequent development of a hitherto noncommercial oil field discovery dating back to 1969. This was accomplished despite the fact that Cook Inlet is one of the most inhospitable offshore areas in the world; there are thirtyfoot tides, moving ice floes in the winter and there are no derrick barges. The platform was assembled in a floating floatover operation in a deep-water bay in lower Cook Inlet. The assembled platform, supported on a barge, was towed to location in upper Cook Inlet and held in place at high tide with several tugs. As the tide ran out the legs reached bottom and the barge was removed. Foundation piles were driven using the pre-installed platform cranes. Introduction The Redoubt Shoal field in Cook Inlet, Alaska, see Figures 1 and 2, was discovered by Amoco (then PanAm) in 1969, but was not deemed commercial at the time. Forest Oil Corporation (then Forcenergy) took over the acreage in 1996 and, following a 3D seismic survey, concluded that the field could be commercial. To confirm this, however, required the drilling of at least two and possibly four appraisal wells. Confirming the commerciality of an offshore prospect is usually done by drilling one or more expendable appraisal wells with a mobile drilling unit. For remote Cook Inlet this method is cost prohibitive, because the equipment has to be mobilized from out-of-state and a single appraisal well was estimated to cost some $25 to 30 million in 1997. Installing a platform in Cook Inlet the "conventional" way is also cost prohibitive, because there is no longer any heavy lifting equipment available on the West Coast and such a platform was estimated to cost $ 60 to 80 million. As an alternative Forest decided to investigate the possibility of installing an "exploratory" drilling structure. Requirements for a minimum structure were:capability to support a 20,000-foot modular drilling rig,installation without heavy lifting equipment,feasibility to be converted into a permanent platform,easy removal in case the prospect did not pan out, andrelocatable to another Cook Inlet location. A number of alternative platform concepts were developed by Redondo Beach, California consultant Belmar Engineering and further investigated for feasibility by Brown & Root in Houston. The selected concept requires no heavy lifting equipment and uses the tide to install the platform. To keep costs down, the platform, which was named Osprey, is located in 45 feet MLLW about two miles from shore rather than in much deeper water, four miles from shore, where the Redoubt Shoal field is located. The lower platform and future pipeline costs offset the increased extended reach drilling costs.

Construction safety and health management has improved significantly following the Occupational Safety and Health Act of 1970. In response to this legislation, contractors began implementing safety programs to reduce occupational safety and health hazards on construction sites. Researchers recently found that the current process of selecting specific elements for a safety program is informal. This paper describes the results of a recent study designed to determine the relative effectiveness of safety program elements by quantifying their individual ability to mitigate construction safety and health risks. In order to determine the effectiveness of individual safety program elements, the following research activities were performed: (1) an appropriate safety risk classification system was created using an aggregation of relevant literature; (2) highly effective safety program elements were identified in literature; and (3) the ability of each safety program element to mitigate a portion of each of the safety risk classes was quantified using the Delphi method. The results of the research indicate that the most effective safety program elements are upper management support and commitment and strategic subcontractor selection and management and the least effective elements are recordkeeping and accident analyses and emergency response planning. It is expected that the data presented in this paper can be used to strategically select elements for a safety program, target specific safety and health risks, and influence resource allocation when funds are limited.

The Safety Risk Library [1] is a structured database [2] that integrates knowledge drawn from multiple sources to address the problem of information disaggregation in the construction industry. This knowledge base maps construction safety risk scenarios to treatment suggestions that help designers implement the concept of prevention through design. In the context of the Safety Risk Library, risk scenarios are characterised by six data categories based on a formalised ontology [3]. To build the first iteration of the Safety Risk Library, nine different risk scenarios were identified and mapped to relevant risk treatments in focus groups. Subsequently, the Safety Risk Library was pilot tested in six construction projects, and user feedback and input were used to expand the list of risk scenarios and treatment prompts. Additionally, public press releases reporting construction accidents were analysed to identify and characterise risk scenarios, which were then mapped to appropriate treatment suggestions and included in the Safety Risk Library. This dataset can assist construction industry stakeholders in identifying, characterising, communicating and mitigating safety risks in construction projects. It can also be integrated into building information modelling environments to assist designers to implement prevention through design.

Optimization of transmission tower structures is traditionally based on either optimization of members sizes with fixed topographical shape or based on structural analysis modelling strategies without taking cognizance of fabrication and constructability issue facing the contractors . This paper look into an integrated optimum design approach strategies whereby topographical factor is simultaneously integrated with the structural modelling strategy using truss and truss-beam analysis taking cognizance of fabrication cost in the construction of the transmission tower. The topographical algorithm is based on changing the inclination degree of the legs of the tower initially with optimum individual members sizing and structural modelling strategies. There after rationalized member sizes are performed through member groupings for the ease fabrication and construction of the transmission tower. First the weight optimizations on individual members are computed and designed to achieve the least weight of the overall structure using the truss and truss-beam modelling strategies. Subsequently the individual members are group as member grouping to achieve the the optimum fabrication in terms of cost and ease of fabrication of the tower. The optimum weight using topographical algorithm obtained for the transmission tower is 10,924 kg for singular members and 18,430 kg for element grouping at 10 o inclination angle after taking due cognizance of foundation loadings and deflections. Optimum design based on topographical algorithm for fabrication cost and ease of construction play a crucial role in the sustainable design and construction of the power transmission tower structures.

Frequent extreme climate events and rapid global urbanization have amplified the occurrence of accidents such as waterlogging or the overflow of pollution in big cities. This has increased the application scenarios of large-sized deep drainage tunnel projects (LSDDTPs). The scientific and accurate evaluation of the construction safety risks of LSDDTP can effectively reduce the corresponding economic losses and casualties. In this paper, we employed the hierarchical holographic model to construct the safety risk list of LSDDTPs in terms of the risk source and construction unit. Based on social network analysis, we then screened key indicators and calculated the weights of all secondary indicators from the correlation between risk factors. We subsequently developed a construction safety risk assessment model of LSDDTPs based on the matter-element extension method. The Donghu Deep Tunnel Project in Wuhan, China, was selected as a case study for the proposed method. The results of empirical research demonstrated that eight indicators (e.g., failure to effectively detect the change of the surrounding environment of the tunnel project) were key factors affecting the construction safety risk of IV, which is within the acceptable risk level. Our proposed model outperformed other methods (the fuzzy comprehensive evaluation, analytic hierarchy process, entropy weight method, and comprehensive weight method) in terms of scientific validity and research advancements.

Accident prevention through design (PtD): Integration of building information modeling and PtD knowledge base

Simulation of tracer dispersion from elevated and surface releases in complex terrain

A hybrid method based on the structural equation model (SEM) and a fuzzy cognitive map (FCM) was developed to study the influences of the construction safety risks (CSR) of metro tunnels constructed by the mining method on the project risk (PR). An SEM was used to identify and verify the correlations between the CSR and PR. An FCM was developed adopting the verified standardized causality and path coefficient in the SEM. On this basis, predictive reasoning and diagnostic reasoning were performed in the framework of an FCM to simulate the CSR and PR. The feasibility of the developed method was validated based on the construction project of a metro tunnel in Wuhan City, China. The results show that (1) the cause concept node C2 (tunnel excavation) shows the strongest positive correlation with the target concept node CT (PR). According to their risks, the construction stages are ranked in descending order as C2 (tunnel excavation), C1 (advanced support), C6 (auxiliary measures), C4 (structure waterproofing), C3 (primary support), and C5 (secondary lining). (2) The target concept node CT is most sensitive to changes in the cause concept nodes C2 and C1. (3) Close attention should be paid to key risks, such as X9 (over-excavation and under-excavation) and X8 (unreasonable determination of excavation footage and sequence) in stage C2. Originality and significance: (1) A hybrid method that can simulate the dynamic interaction between the CSR and PR is proposed. (2) A new perspective for the dynamic evaluation of a PR is provided. (3) The method can be used as a decision-making tool for controlling the PR.

With the acceleration of globalization, trade between countries has become more and more frequent; as a kind of commonly used heavy lifting equipment, the influence of the quayside crane on environment during the production stage has attracted wide attention. In this paper, the world’s largest quayside crane manufacturer was selected as the study object. The environmental load of five workshops (NC pre-treatment workshop, assembling workshop, sand milling workshop, painting workshop and steel structure workshop) involved in the quayside crane (QC) production stage was studied by using the ReCiPe model; the normalized values of the 14 overall pollutants in each workshop were 1248.64, 576.75, 214.27, 85.26 and 76.69, respectively. The results showed that the sand milling workshop was the biggest electricity consumer of all processes. The sensitivity analysis revealed that the environmental pollution load was the most sensitive to the electricity consumption; the scenario analysis indicated that with the proportion of China’s renewable resources in the process of electricity generation becoming larger and larger, in comparison with that of in 2015, up to 2050, the quantity of PM 2.5 generated during the production process of QC will drop from 832 to 408 kg (high-speed development)/342 kg (low-speed development), and it is expected that the China’s haze problem could be effectively curbed in the future. Finally, the research results of this article also pointed out the direction for the future technical innovation of the QC industry.

The fundamental challenge of complex (typically mountainous or urban) terrain for radio-frequency systems is that a direct line-of-sight is difficult or impossible to achieve between a radio transmitter and receiver. In the context of ground-based military operations, occupying line-of-sight positions to optimize communications or surveillance capabilities often exposes Soldiers and/or equipment to unacceptable risks from both conventional and electronic warfare. Propagation models for tactical use commonly analyze terrain only in the vertical plane containing both transmitter and receiver in order to simplify both the required data and computational burdens. However, these advantages come at the cost of ignoring reflections from topography within and outside the vertical plane path, which can have serious implications for radio-frequency direction finding, surveillance, and high-speed data transfer in complex terrain. This work summarizes our efforts to address these issues by developing a hybrid path loss model, one specifically designed for ground-to-ground radio links in complex rural terrain. The model uses an existing international-standard vertical plane diffraction model (VPM) to account for path losses associated with obstacles, and then augments those results with geospatially derived terrain reflection/scattering effects. Our prototype Terrain Scatter Augmented Vertical Plane Model (TSAVPM) provides physically credible path loss results in complex terrain at tactically relevant spatial scales (∼250 sq. km) and computational costs (under 40 seconds on a single 4.2 GHz central processing unit).

In recent studies of atmospheric turbulent surface exchange in complex terrain, questions arise concerning velocity-sensor tilt corrections and the governing flow equations for coordinate systems aligned with steep slopes. The standard planar-fit method, a popular tilt-correction technique, must be modified when applied to complex mountainous terrain. The ramifications of these adaptations have not previously been fully explored. Here, we carefully evaluate the impacts of the selection of sector size (the range of flow angles admitted for analysis) and planar-fit averaging time. We offer a methodology for determining an optimized sector-wise planar fit (SPF), and evaluate the sensitivity of momentum fluxes to varying these SPF input parameters. Additionally, we clarify discrepancies in the governing flow equations for slope-aligned coordinate systems that arise in the buoyancy terms due to the gravitational vector no longer acting along a coordinate axis. New adaptions to the momentum equations and turbulence kinetic energy budget equation allow for the proper treatment of the buoyancy terms for purely upslope or downslope flows, and for slope flows having a cross-slope component. Field data show that new terms in the slope-aligned forms of the governing flow equations can be significant and should not be omitted. Since the optimized SPF and the proper alignment of buoyancy terms in the governing flow equations both affect turbulent fluxes, these results hold implications for similarity theory or budget analyses for which accurate flux estimates are important.

The construction industry has a higher rate of work accidents than other industries. As a proactive approach to safety management, Construction Hazard Prevention through Design (CHPtD) can significantly eliminate or reduce construction safety risks. This method consists of three indices namely Likelihood, Consequence and Exposure. Likelihood and consequence index of 19 construction jobs using 2018 injury and death data. Only 4 types of work are shown in this case. The findings conclude that the index of relative mortality frequency (RFI) of roofers (47-2180) and the index of relative frequency of day-going injuries (RDAIFI) of construction workers (47-2060) are relatively high. In addition, construction equipment operators relative day-to-day injury severity (RDAIS) rates (47–2070) are 3.3 times that of roof operators (47–2180). These results validate that using plug-ins in Revit can quickly calculate the construction safety risks of various design plans in a very short time and show that the plug-ins developed have very good engineering application value.

Mountainous areas require appropriate measurement strategies to cover the full spectrum of details concerning the energy exchange at the Earth’s surface and to capture the spatiotemporal distribution of atmospheric dynamic and thermodynamic fields over them. This includes the range from turbulence to mesoscale processes and its interaction. The surface energy balance needs appropriate measurement strategies as well. In this paper, we present an overview of important experiments performed over mountainous terrain and summarize the available techniques for flow and energy measurements in complex terrain. The description includes ground-based and airborne in situ observations as well as ground-based and airborne remote sensing (passive and active) observations. Emphasis is placed on systems which retrieve spatiotemporal information on mesoscale and smaller scales, fitting mountainous terrain research needs. Finally, we conclude with a short list summarizing challenges and gaps one faces when dealing with measurements over complex terrain.

<p>Observations from six eddy-covariance stations in the Austrian Inn Valley reveal a strong spatial variability in near-surface turbulent fluxes. While the stations are located within an approximately 6.5 km long section of the valley and thus within an area similar or even smaller than a single grid cell in current global weather forecasting models, the sites strongly differ in terms of topography and land use. Observed magnitudes of sensible and latent heat fluxes are driven by the solar incoming radiation and thus affected by the local slope angle and orientation, with further influences from the land use on the partitioning of the available energy into sensible and latent heat fluxes. In addition, the locally induced thermal slope- and valley-wind circulation impact the diurnal cycles of the turbulent fluxes. To correctly represent turbulent exchange in mountainous terrain in numerical models, the models thus need to represent all these conditions and processes correctly. We are running WRF simulations with a 1-km grid spacing as part of an ongoing project to evaluate land-surface models and turbulence parameterizations over complex terrain. The simulations are used to determine how sensitive the modeled land-atmosphere exchange is to inaccuracies in the topography and land use, which are unavoidable at this spatial resolution, and whether the model can reproduce the observed spatial variability.</p>