This paper explores Vygotsky's theory of scientific concepts. It does so in direct relation to forms of mathematical pedagogy which strive to develop more meaningful activity than the dominant drill and memory-based practice. In doing so it develops the beginnings of a systematic theoretical explanation, and justification, of such approaches to teaching.

Many surgeons in low-resource settings do not have access to safe, affordable, or reliable surgical drilling tools. Surgeons often resort to non-sterile hardware drills because they are affordable, robust, and efficient, however impossible to sterilize. A promising alternative is to use a Drill Cover system (a sterilizable fabric bag plus surgical chuck adapter) so that a non-sterile hardware d...

The present work deals with developing a fuzzy back propagation neural network scheme for prediction of drill wear. Drill wear is an important issue in the manufacturing industries, which not only affects the surface roughness of the hole but also influences the drill life. Therefore, replacement of drill at an appropriate time is of significant importance. Flank wear in a drill which depends u...

This paper presents a new thermal model for bone drilling with applications to orthopaedic surgery. The new model combines a unique heat-balance equation for the system of the drill bit and the chip stream, an ordinary heat diffusion equation for the bone, and heat generation at the drill tip, arising from the cutting process and friction. Modeling of the drill bit-chip stream system assumes an...

The analysis of drill cutting angles is important for the design of high-performance drill geometry. The cutting angles along the cutting edge of a drill are determined by the combination of its flute and flank surfaces. This paper examines the analysis of both flute and flank surface models and the evaluation of drill cutting angles. A new mathematical model for an arbitrary drill flute face i...

Drilling is the most frequently employed operation of secondary machining for fiber-reinforced materials owing to the need for structure joining. Delamination is one of the serious concerns during drilling. Practical experience shows that an eccentric twist drill or an eccentric candle stick drill can degrade the quality of the fiber reinforced material. Comprehensive delamination models for th...

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 (...

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 ...