A parametric experimental investigation of a scramjet nozzle at Mach 6 with Freon and argon or air used for exhaust simulation

A parametric experimental investigation of a scramjet nozzle was conducted with a gas mixture used to simulate the scramjet engine exhaust flow at a free-stream Reynolds number of approximately 6.5 x 10(exp 6) per foot. External nozzle surface angles of 16, 20, and 24 deg were tested with a fixed-length ramp and for cowl internal surface angles of 6 and 12 deg. Pressure data on the external nozzle surface were obtained for mixtures of Freon and argon gases with a ratio of specific heats of about 1.23, which matches that of a scramjet exhaust. Forces and moments were determined by integration of the pressure data. Two nozzle configurations were also tested with air used to simulate the exhaust flow. On the external nozzle surface, lift and thrust forces for air exhaust simulation were approximately half of those for Freon-argon exhaust simulation and the pitching moment was approximately a third. These differences were primarily due to the difference in the ratios of specific heats between the two exhaust simulation gases. A 20 deg external surface angle produced the greatest thrust for a 6 deg cowl internal surface angle. A flow fence significantly increased lift and thrust forces over those for the nozzle without a flow fence

Investigation of effect of propulsion system installation and operation on aerodynamics of an airbreathing hypersonic airplane at Mach 0.3 to 1.2

Results from an investigation of the effects of the operation of a combined turbojet/scramjet propulsion system on the longitudinal aerodynamic characteristics of a 1/60-scale hypersonic airbreathing launch vehicle configuration are presented. Decomposition products of hydrogen peroxide were used for simulation of the propulsion system exhaust

Impact of new technology on timber harvesting costs: Evaluation methods and literature

Timber harvesting and transport are crucial components of the cost of delivered wood to forest products processing facilities. In fact, harvesting and delivering wood often costs more than the entire costs of growing wood until harvest. As such, timber harvesting research and development are important. Additionally, research in this area is worthwhile because efficiency gains, cost improvements, and environmental benefits due to timber harvesting research can be realized in a very short time period, rather than the decades-long wait required for research investments in timber growing. This paper provides an overview of the means of measuring the impact of new technology on timber harvesting costs. In recent years, there have been many efforts to increase research for developing better harvesting equipment and methods. In conjunction with these efforts, greater demands have been made for research efficiency and accountability (Silversides et al. 1988); several studies have therefore been completed to measure the impacts of timber harvesting research and development. These studies, other means of evaluating timber harvesting research, and suggestions for future evaluations are discussed

The recognition and application of security risk management in corporate governance

Security as a profession and discipline has emerged principally in the later half of the twentieth century and has developed to become a more defined, usual, respectable and visual part of management. This study aimed to determine the degree of recognition and application of security risk management to corporate governance practices in Australia. Formal research design used descriptive research methodology, consisting of a literature review, primary document analysis and a questionnaire survey to collect data. This research was contrasted to a Corporate Governance Security Model formulated to determine if the model is applicable to the recognition, or application, of a security function to the Australian Stock Exchange (\u27ASX\u27) Corporate Governance principles. A major finding of this study is that security functions and responsibilities are poorly recognised and documented by Australia\u27s largest public company boards. A majority of directors will have no experience or qualifications in security risk management and this is likely to be reflected down through the organisation resulting in low to medium security awareness and culture. Corporate governance statements from companies listed on the ASX/S&P 200 strongly suggests that security related risks are not widely considered as part of the corporate governance framework. With limited application of security in the corporate governance framework, there is less focus on security related behaviour within the codes of conduct held by a majority of public companies. This can have an adverse impact on corporate ethics, internal controls and crisis response capabilities. The study developed a model which implements security risk management functions to the corporate governance framework in order to formally recognise and promote effective management of security risk and compliance. Applying security as a business process to support long term revenue was found to benefit corporate reputation and compliments other risk and business management practices. Security of information and confidentiality is enhanced to encourage reports of misconduct within the company, generating a security and reporting culture. Security functions are currently limited to form part of internal controls within the operating environment and generally viewed as a cost centre which does not contribute to revenue. Security functions are not holistically applied across the organisation or within the corporate governance framework. There are a number of recommendations resulting from the study and are primarily concerned with the continued need for research into the application and recognition of security within the hierarchy of executive and business management

The Development of an 8-inch by 8-inch Slotted Tunnel for Mach Numbers up to 1.28

An 8-inch by 8-inch transonic tunnel model with test section slotted on two opposite walls was constructed in which particular emphasis -was given to the development of slot geometry, slot-flow reentry section, and short-diffuser configurations for good test-region flow and minimum total-pressure losses. Center-line static pressures through the test section, wall static pressures through the other parts of the tunnel, and total-pressure distributions at the inlet and exit stations of the diffuser were measured- With a slot length equal to two tunnel heights and 1/14 open-area-ratio slotted walls) a test region one tunnel height in length was obtained in which the deviation from the mean Mach number was less than +/- 0.01 up to Mach number 1.15. With 1/7 open-area-ratio slotted walls, a test region 0.84 tunnel heights in length with deviation less than +/- O.01 was obtained up to Mach number 1.26. Increasing the tunnel diffuser angle from 6.4 to 10 deg. increased pressure loss through the tunnel at Mach number 1.20 from 15 percent to 20 percent of the total pressure. The use of other diffusers with equivalent angles of 10 deg. but contoured so that the initial diffusion angle was less than 10 deg. and the final angle was 200 reduced the losses to as low as 16 percent. A method for changing the test-section Mach number rapidly by controlling the flow through a bypass line from the tunnel settling chamber to the slot-flow plenum chamber of the test section was very effective. The test-section Mach number was reduced approximately 5 percent in 1/8 second by bleeding into the test section a flow of air equal to 2 percent of the mainstream flow and 30 percent in 1/4 second with bleed flow equal to 10 percent of the mainstream flow. The rate of reduction was largely determined by the opening rate of the bleed-flow-control valve

Expression of osterix Is Regulated by FGF and Wnt/β-Catenin Signalling during Osteoblast Differentiation

Osteoblast differentiation from mesenchymal cells is regulated by multiple signalling pathways. Here we have analysed the roles of Fibroblast Growth Factor (FGF) and canonical Wingless-type MMTV integration site (Wnt/β-Catenin) signalling pathways on zebrafish osteogenesis. We have used transgenic and chemical interference approaches to manipulate these pathways and have found that both pathways are required for osteoblast differentiation in vivo. Our analysis of bone markers suggests that these pathways act at the same stage of differentiation to initiate expression of the osteoblast master regulatory gene osterix (osx). We use two independent approaches that suggest that osx is a direct target of these pathways. Firstly, we manipulate signalling and show that osx gene expression responds with similar kinetics to that of known transcriptional targets of the FGF and Wnt pathways. Secondly, we have performed ChIP with transcription factors for both pathways and our data suggest that a genomic region in the first intron of osx mediates transcriptional activation. Based upon these data, we propose that FGF and Wnt/β-Catenin pathways act in part by directing transcription of osx to promote osteoblast differentiation at sites of bone formation

Loss of infectivity of poliovirus 1 in river water under simulated field conditions

The effects of light, virus concentration, and turbidity on the rate of loss of infectivity (LOI) of poliovirus 1 were investigated in two test systems, which utilized flowing river water. Two levels of each variable were used in a 23 confounded factorial design. The seeded systems were sampled at regular intervals to establish LOI rates. Virus infectivity was measured by plaque assay. Loss of infectivity followed a two-component curve; an initial, rapid phase followed by a second, slower component. The slopes of the two components were examined by the analysis of variance to determine the potential influence of each variable. Both light and turbidity exerted a significant influence on the LOI rate in the second component of the LOI curve and also in the transition period between the two components; however, during the initial, rapid phase none of the variables influenced the LOI rate (at the 0.05 significance level). This research demonstrates the significance of light as a virucidal component in the aquatic environment.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/23757/1/0000730.pd

Swim-Training Changes the Spatio-Temporal Dynamics of Skeletogenesis in Zebrafish Larvae (Danio rerio)

Fish larvae experience many environmental challenges during development such as variation in water velocity, food availability and predation. The rapid development of structures involved in feeding, respiration and swimming increases the chance of survival. It has been hypothesized that mechanical loading induced by muscle forces plays a role in prioritizing the development of these structures. Mechanical loading by muscle forces has been shown to affect larval and embryonic bone development in vertebrates, but these investigations were limited to the appendicular skeleton. To explore the role of mechanical load during chondrogenesis and osteogenesis of the cranial, axial and appendicular skeleton, we subjected zebrafish larvae to swim-training, which increases physical exercise levels and presumably also mechanical loads, from 5 until 14 days post fertilization. Here we show that an increased swimming activity accelerated growth, chondrogenesis and osteogenesis during larval development in zebrafish. Interestingly, swim-training accelerated both perichondral and intramembranous ossification. Furthermore, swim-training prioritized the formation of cartilage and bone structures in the head and tail region as well as the formation of elements in the anal and dorsal fins. This suggests that an increased swimming activity prioritized the development of structures which play an important role in swimming and thereby increasing the chance of survival in an environment where water velocity increases. Our study is the first to show that already during early zebrafish larval development, skeletal tissue in the cranial, axial and appendicular skeleton is competent to respond to swim-training due to increased water velocities. It demonstrates that changes in water flow conditions can result into significant spatio-temporal changes in skeletogenesis