Influence of rock powder on the behaviour of an organic soil

Bulletin of Engineering Geology and the Environment - This paper aims to present the use of rock powder as an agent to improve the behaviour of organic soil. The rock powder, a waste material, was...     

Use of float consumption rate in resource leveling of construction projects

The management of resources has been claimed to be as important as scheduling methods. Inefficiency in managing resources may bring about severe delays and cost overruns caused by resource shortages in some cases and/or idle resources in others. Therefore, resources should be utilized efficiently to prevent project failures. Resource leveling is one of the approaches that are used for the management of resources. It aims to minimize fluctuations, peaks, and valleys in resource utilization without changing the completion time of a project and the number of resources required. Although the main principle behind traditional resource leveling is achieving an even flow of resources while the original project duration remains unchanged, the literature supports the need to develop an efficient model that discriminates among the activities that are selected for participation in resource leveling. For this purpose, this study has developed a model that considers the float consumption rates of activities in resource leveling. The float consumption rate is the percentage that is set to determine the maximum amount of float which will be consumed to shift the start time of the activity. The proposed model allows a scheduler to assign float consumption rates to each activity that can be used during the resource leveling procedure. When the required information is inputted, the proposed model automatically changes the required daily resources as it shifts the noncritical activities along their available total float times. The proposed model is expected to minimize the likelihood of severe delays and cost overruns. The model is demonstrated by constructing a network and its resource utilization histograms.     

A FE technique to improve the accuracy of drawbead models and verification with channel drawing experiments of a high-strength steel

A drawbead modeling technique is presented to improve the accuracy of finite element simulations in terms of part draw-in and thickness predictions and validated with channel drawing experiments of a high-strength low-alloy steel. The drawing characteristics of 1.5-mm thickness blanks are obtained with strip drawing tests with a round drawbead, and drawbead model parameters are computed for three bead settings. The consequences of bending deformation cycles are determined experimentally on strip draw-in and thickness values, and model limitations of equivalent drawbead elements are also assessed for test conditions in which the drawbead restraint force is lower than the sectional yield limit. The influence of omitted drawbead geometry and overestimated drawbead-exit thickness are described using an analytical model, and a closed form expression is obtained to correct draw-in model error under sectional deformation conditions. Blank thickness and equivalent strain at the drawbead exit are additional drawbead model parameters of the proposed technique. Then, drawing simulations of a variable section, open-ended channel part are performed. The drawbead design, bead settings and tool-blank interface conditions are identical to those in strip drawing tests. Computed draw-in and thickness distributions were compared with measurements on produced channels using an experimental channel draw die. It is concluded that simulation models, based on drawbead force parameters only, overestimate blank thickness at the die entry and bring about relatively high draw-in values along part border lines. The thickness distribution predicted with proposed technique shows an enhanced correlation with on-part thickness measurements, and bead penetration effects on channel border lines are also simulated acceptably.     

Modeling groundwater flow in the agricultural area of Gümüşhacıköy (Amasya, Turkey)

The Gümü?hac?köy Plain is the most productive agricultural area in the central/northern part of Turkey. Although the Quaternary/Pliocene granular deposits beneath the Plain have formed an important aquifer/water resource, excessive pumping in the last two decades, mainly for irrigation, has resulted in a significant depletion of the reservoir with some 30% of the total resource being lost in the last 40 years. The paper reports a groundwater flow model developed to allow the sustainability of the groundwater resource to be monitored such that appropriate measures can be undertaken.     

Characterization of dual-electrode CMUTs: demonstration of improved receive performance and pulse echo operation with dynamic membrane shaping

A 1-D dual-electrode CMUT array for intracardiac echocardiography (ICE) with a center frequency of 8 MHz has been designed, fabricated, and used to demonstrate the potential of dual-electrode CMUTs. Using a dual-electrode CMUT, 9 dB higher receive signal level is obtained over the 6 dB fractional bandwidth as compared with a conventional CMUT with an identical center electrode biased close to its collapse voltage. Because the same device shows a 7.4 dB increase in maximum pressure output, 16.4 dB overall improvement in transduction performance has been achieved as compared with conventional CMUT. A net peak output pressure of 1.6 MPa on the dual-electrode CMUT membrane with tone burst excitation at 12 MHz is also reported. The frequency response of the dual-electrode CMUT is similar to that of a conventional CMUT with the same membrane geometry with about 15% increase in the center frequency. Monostatic operation of dual-electrode CMUTs shows that the high performance of the transducer is applicable in typical pulse-echo imaging mode of operation. With dynamic shaping of the CMUT membrane to optimize the transmit-and-receive modes of operation separately during each pulse-echo cycle, dual-electrode CMUT is a highly competitive alternative to its piezoelectric counterparts.