Accuracy is the key issue in the precision forging. Geometric and dimension errors are the two significant defects found in most of near net or net shape manufacturing process. It becomes more critical for complex part such as an AUV propeller blade. In this study, geometric error was quantified by comparing the blade profile obtained from nominal geometry of the blade and the profile construct...

We follow the approach used by Davies and Pringle (1981) and discuss the trans-sonic substage of the propeller regime. This substage is intermediate between the supersonic and subsonic propeller substages. In the trans-sonic regime an envelope around a magnetosphere of a neutron star passes through a kind of a reorganization process. The envelope in this regime consists of two parts. In the bot...

Seagrasses play a critical role in the function and structure of coastal ecosystems, and they are an important habitat for a variety of marine organisms. Damage to seagrass beds from boat propellers is significant in many areas. Recognizing the need to protect this valuable habitat, three voluntary no motor zones were established in Redfish Bay, Texas. This study was designed to test the effect...

A literature review, a datasheet review, and in-house experimental data were used to obtain a real-world comparison between bio-mimetic pectoral fins and traditional propeller-based thrusters. Only power consumption, forward thrust, and propulsive efficiency are compared. Scaling trends for both propulsion forms are discussed. Traditional thrusters are determined to be more efficient than curre...

This paper focuses on the modelling and simulation of unsteady sheet cavitation in marine propeller flows. In the first part of the paper, the mathematical model based on potential flow theory is introduced and the numerical scheme is derived. The novelty of the presented calculation method refers to the unsteady partial sheet cavitation model which has been implemented into the in-house panel ...

Instrumental evaluations (e.g. Dobrzynski, InterNoise 90) showed that propeller noise can be reduced by asymmetrical blade spacing. Compared to conventional propellers with 6 blades and symmetrical spacing of 60°, propellers with asymmetric spacing of 15° produce about 3 dB(A) less level, in particular for high helical blade tip Mach numbers HBTMN. Since the aerodynamic propeller performance is...

Diverse pathogenic bacteria produce transmembrane receptor Ser/Thr protein kinases (STPKs), but little is known about the signals mediated by these "eukaryotic-like" proteins. To explore the basis for signaling in the bacterial STPK receptor family, we determined the structure of the sensor domain of Mycobacterium tuberculosis PknD. In two crystal forms, the PknD sensor domain forms a rigid, si...

An unsteady actuator disk model is constructed in order to understand unsteadiness in crashback operation of a marine propeller as a competition between two flows of opposite direction: reversed flow through the propeller and the ambient flow due to motion of the vessel. The large eddy simulation methodology is applied to predict the flow corresponding to forward and crashback modes of operatio...

Distributed electric propulsion technology has great potential and advantages in the development of drones. In this paper, to study slipstream effect distributed propellers, actuator disk method was used verify a single propeller, calculated thrust good agreement with test results. Then, based on method, influence different installation positions studied, propeller layout optimized by genetic a...

BACKGROUND Telehealth strategies for asthma have focused primarily on adherence to controller medications. Telemonitoring of short-acting β-agonist (SABA) focuses on patterns of use and may allow more timely action to avert exacerbations. Studies assessing this approach are lacking. OBJECTIVE This pragmatic controlled study was designed to measure real-world effectiveness of the Propeller Hea...