Designing a high-performance twist drill is difficult due to the complex relationship between drill geometry and numerous and conflicting design goals. Earlier approaches of computer-aided twist drill design are limited to only few design aspects. This article presents a new holistic method of using computing power for twist drill design and optimization. A complete drill geometry model is used...

Weight on the bit is accomplished by running in the hole, between the bit and the drill pipe, several lengths of extremely heavy thick-walled pipe, called “drill collars”. Drill pipe may weigh up to 30 kg/m. Drill collars, of larger diameter than drill pipe and of constant diameter throughout, can weigh up to IS0 kg/m. The full hanging weight of the whole assembly in the blocks in the derrick (...

this study evaluated direct drilling planters used for wheat cultivation in khorasan-e razavi province. a randomized complete block design with three replications was used. the treatments were direct drilling of wheat plants into wheat residue using the following direct planters: (1) sfoggia (13-25), (2) baldan (spd3000), (3) tondar (spd 2500), (4) semeato (shm 11/13). the parameters measured w...

PURPOSE To determine whether a wire-guided single drill protocol could be utilized without causing an increase in bone temperature beyond those seen with the traditional techniques of sequential drilling with and without a drill guide. MATERIALS AND METHODS A bovine femoral bone model was used with thermocouples and infrared temperature measurements to record thermal increase of the bone and ...

PURPOSE It is difficult for emergency physicians to plan and execute a disaster medical response drill while conducting their daily work activities. Readily available drill preparation manuals are therefore essential, alongside assessment methods to ensure quality. Here, we propose email text analysis as a manual assessment method, and investigate its validity. METHODS The preparation status ...

The drill makes use of four rods to obtain the full length drill string which allows to reach a penetration depth of 2 meters. The first rod is the real drill tool with sample collection capability; the other 3 rods are extension rods. The real drill tool is installed at the mandrel during launch, the other three rods are stored in a dedicated rod magazine together with a back up drill tool. Al...

BACKGROUND Various techniques for quadriceps tendon repair have been described with biomechanical studies suggesting greater failure threshold with longitudinally placed drill holes. 1 The current gold standard for repair uses 3–4 sutures 2 passed through parallel longitudinal transpatel-lar bone tunnels. We describe a simple and reproducible technique Figure 1 Acufex ® Director™ Drill Guide po...

We present a data exploration system equipped with smart drill-down, a novel operator for interactively exploring a relational table to discover and summarize "interesting" groups of tuples. Each such group of tuples is represented by a rule. For instance, the rule (a, b, ★, 1000) tells us that there are a thousand tuples with value a in the first column and b in the second column (and any valu...

Severe environment in deep ocean affects operating reliability and security of coring drill. Adopting heave motion signal measured by accelerometer to confirm heave compensation of coring drill, the compensation control method is proposed using disturbance observer to restrain the disturbance. Then, the disturbance observer is designed. The heave motion simulation for coring drill is done with ...

Due to the lower tool as the research object to analyze the vibration of the drill string, causes the loss of the low order natural frequency of the drill string and the inherent vibration mode, give rise to the distortion and error of the result from the transient analysis of the drill string. For this purpose, the whole drill string of the deep wells is studied in the article, build the mecha...