Methodology for Designing Structures to Withstand Extreme Environments: Performance Based Specifications

Existing guidelines in BS 8500 allow the selection of concrete mix based on variables such as compressive strength, maximum water to binder ratio, minimum cement content and minimum cover thickness. This approach does not guarantee the durability and expected performance of the concrete structure in a given environment. One alternative is to develop performance- based specifications that supplement the existing guidelines in BS 8500, by specifying the required performance of concrete in terms of measurable properties such as resistance to environmental penetrations. This paper demonstrates one of such methodology for developing performance-based specifications for concretes exposed to marine environments. Chloride ingress related durability problem being critical in a marine environment, the reliability and repeatability of the different test methods for assessing the rate of chloride ingress is discussed first. Furthermore, a numerical simulation model is used to explore the test data to obtain long-term chloride ingress trends. Based on this, guidelines for selecting appropriate concrete mixes for a marine exposure is presented and discussed

COST OPTIMIZATION OF INVENTORY SYSTEM IN TWO-ECHELON WITH TWO SUPPLIERS

This paper presents a continuous review two echelon inventory system. The operating policy at the lower echelon is (s, S) that is whenever the inventory level traps to s on order for Q = (S-s) items is placed, the ordered items are received after a random time which is distributed as exponential. We assume that the demands accruing during the stock-out period are lost. The retailer replenishes their stock from the regular supplier which adopts (0, M) policy, M = nQ. When the regular supplier stock is empty the replacement of retailer stock made by the outside supplier who adopts (0, N) policy N = nQ. The joint probability disruption of the inventory levels of retailer, regular supplier and the outside supplier are obtained in the steady state case. Various system performance measures are derived and the long run total expected inventory cost rate is calculated. Several instances of numerical examples, which provide insight into the behavior of the system are presented

The Influence of Different European Cements on the Transport and Early-age Properties of Concrete in the Cover-zone

The use of in situ tests for performance based specification would require demonstration of their suitability to distinguish the quality of concrete. With the introduction of new European Standards for cements, this would mean concretes produced with these new cements should be classified for their quality using the performance tests. It is generally believed that transport properties of concrete are related to their durability and hence the measurement of these properties can form the basis of performance based specifications. This paper reports data indicating that transport properties measured at 28-days for concretes manufactured with different European cements and water-binder ratios can form the basis of classifying concrete for their durability. The results also demonstrated how the different cements specified in European Standards influence the transport properties and other early-age properties

Influence of chloride ions on progress of carbonation in concretes

Our infrastructure and environment face unprecedented challenges in addressing a low carbon future with limited natural resources, expanding population, increased pollution and climatic uncertainties. Adaptation and innovations must therefore play a vital role in addressing the anticipated wide ranging complex scenarios ahead. The environment in which construction materials will need to function will become far more complex and aggressive and hence a fundamental revaluation of the most appropriate materials for future infrastructure and environment will be required in order to tackle those challenges. This paper focuses on a class of construction materials, both old and new, based on magnesia (MgO). They include a wide range of materials from those that contain MgO as a small additive to those which solely consist of MgO. They include concrete with MgO as an expansive additive, pervious concrete, alkali-activated cements, magnesium phosphate cements, carbonated products, stabilising additives for ground improvement, self-healing additives, carbon capture and storage materials and binders for waste 105 and contaminated land remediation. Those materials and products offer a range of technical and sustainability benefits for a range of structural, geotechnical and environmental applications. The paper highlights the applications and benefits that would be achieved with magnesia-bearing construction materials

A Study on Hierarchical Model of a Computer Worm Defense System

This research addresses the problem of computer worms in the modern Internet. A worm is similar to a virus. A worm is a self-propagating computer program that is being increasingly and widely used to attack the Internet. It is considered as a sub-class of a virus because it is also capable of spreading from one computer to another. Worms are also computer programs that are capable of replicating copies of themselves via network connections. What makes it different however is that unlike a computer virus a computer worm can run itself without any human intervention? Because of these two qualities of a worm, it is possible that there will be thousands of worms in a computer even if only one computer worm is transferred. For instance, the worm may send a copy of itself to every person listed in the e-mail address book. The worm sent may then send a copy of itself to every person who is listed in the address book of the person who receives the email. Because this may go on ad infinitum worms can not only cause damage to a single computer and to other persons computer but it can only affect the functionality of Web servers and network servers to the point that they can no longer function efficiently. One example is the .blaster worm

Short term analysis of functional results of acetabular fractures treated by internal fixation with recon plate using kocher-langenbeck approach

INTRODUCTION: About 10 % of pelvic injuries involves acetabulum of which more than 80 % occurred in road traffic accidents and 10.7% in fall victim injuries. Acetabulum being important weight-bearing surface of hip joint, fixation of these fractures becomes extremely important to give congruous stable painless hip joint. This study mainly conducted to analyse the short term functional outcome after stable rigid internal fixation of posterior column and posterior wall in acetabular fractures through Kocher-Langenbeck approach. MATERIALS AND METHODS: This is a prospective study conducted in the Department of Orthopaedic surgery, Government Royapettah hospital. Patients with age more than 18 years and less than 65 years, fractures displaced more than 2 mm including Posterior wall , Posterior column, Transverse, Posterior column with posterior wall, Transverse with posterior wall, T type fractures ( Judet classification),fracture less than 3 weeks with or without posterior hip dislocation were included. Open fractures, local soft tissue problems, severe medical contraindications for surgery, fractures more than 3weeks old, fractures with pre-existing hip joint arthritis, patients with other disorders such as Ankylosing spondylitis, Rheumatoid arthritis, pathological fracture and fractures of types Anterior wall, Anterior column, Anterior column with posterior hemitransverse, Both column fractures (Judet classification).All patients operated through Kocher-Langenbeck approach in prone position. Postoperatively quality of fracture reduction analysed using Matta’s criteria and at 6th month functional outcome analysed using Modified Merle de Aubigne Postel Scoring system. OBSERVATION AND RESULTS: Male patients dominated in our study with ratio of 6.3:1. Posterior column with posterior wall fracture is most common fracture type in our study [5 patients (25%)] followed by Posterior wall fracture [4 patients (20%)]. Out of 19 patients, four patients(20%) had excellent , eight patient(40%) had good , four patient(20%) had fair and three patient(15%) had poor results. Average Functional outcome score was 14.73 for ranging from 11 to 18 (Maximum Score- 18). No patient had heterotopic ossification or post-traumatic osteonecrosis. CONCLUSION: Kocher-Langenbeck approach can be used address almost all the fractures except fractures involving Anterior wall, Anterior column and Bicolumn fracture. Providing prophylaxis against DVT and heterotopic ossification reduces the complications of surgical treatment. The learning curve being relatively slow, proper understanding the fracture pattern and good preop planning will help to minimize the duration of surgery and complications. Keywords

Identification of Random Amplified Polymorphic DNA (RAPD) Markers in Endemic Yellow Catfish, Horabagrus brachysoma (Gunther 1864)

Random amplified polymorphic DNA (RAPD) analysis was applied to individuals of Horabagrus brachysoma sampled from three geographic locations of Western Ghat river systems in India. Of the thirty-two 10-mer RAPD primers screened initially, ten were chosen and used in a comparative analysis of H. brachysoma collected from Chalakkudy, Meenachil and Nethravathi river systems. A total of 124 RAPD fragments were amplified, out of which 49 (39.51%) were found to be shared by individuals of all three river systems. The remaining 75 fragments were found to be polymorphic (60.48%). This confirms the suitability of RAPD markers for the study of population genetic structure in yellow catfish stocks

Deep-sea chondrichthyan composition and abundance in Andaman waters, Indian EEZ-preliminary results based on exploratory survey

Two deep-sea fishery surveys were conducted during 2015 to explore the fish diversity and fishing grounds. Seven deep sea bottom trawl operations were conducted using HOT and HSDT-IInets

Functional analysis of cemented bipolar hemiarthroplasty with medial calcar augmentation for unstable intertrochanteric fractures in elderly

Background: Intertrochanteric fracture is one of the most common fractures among the elderly osteoporotic population, constituting about 50% of hip fractures. These fractures are managed either by fixation using dynamic hip screw (DHS), proximal femur nail (PFN) or by replacement, based on the stability of fracture pattern, age of the patient, quality of bone and associated co-morbid conditions. Prosthetic replacement which is routinely done for femoral neck fractures requires modification when done for trochanteric fractures to improve stability. This study aims to analyse the short term functional outcome of cemented bipolar hemiarthroplasty with medial calcar augmentation for unstable intertrochanteric fractures in elderly.Methods: Our study includes 60 patients of age more than 70 years admitted in our institution during June 2012 to September 2016 with unstable intertrochanteric fractures. All patients operated through posterior approach to hip and cemented hemiarthroplasty with medial calcar augmentation with bone graft was done. Patients were followed up for an average of period of 2 years. Functional outcome was evaluated with Harris Hip score.Results: 28% of cases had excellent outcome. 43% of cases had good and 23% of cases had fair outcome. 2% of cases ended with poor outcome. The in-hospital mortality rate was 3.3%. The survival rate of the patients in this study at the end of one year is 85%. Conclusions: Cemented bipolar hemiarthroplasty with medial calcar augumentation can be considered as a good primary option for elderly unstable intertrochanteric fracture patients with osteoporotic bones and associated co-morbidities.