Research and analysis of harmful road emissions from a two-wheel vehicle engine in laboratory conditions

The subject of this article is the identification of engine exhaust emissions of two-wheel vehicles under laboratory conditions. For this purpose, analysis of road and time emission of gaseous compounds: HC, CO, CO2, NOx from a motorcycle equipped with an engine with a displacement volume of 0.7 dm3 and a maximum power of 55 kW was made. The tests were performed on a dynamometer station designed for testing two-wheel vehicles. The speed characteristic was taken from the European type approval test WMTC, consisting of three parts. Each of these parts lasted 600 seconds and was characterized by a different maximum vehicle speed value. The mobile AXION R/S apparatus part of the PEMS device group was used in the research. What is more, the exhaust emissions results were referred to the values listed by the exhaust emission standard met by the tested vehicle (Euro 4 standard). Laboratory tests presented in the article are only intended as a basis for further research, which includes exhaust emission tests from two-wheel vehicles in real operating conditions.

Lateral Congenital Anomalies of the Pharyngeal Apparatus: Part I. Normal Developmental Anatomy (Embryogenesis) for the Surgeon

Knowledge of the embryogenesis of the pharyngeal apparatus is the only means of understanding the “architecture” of the neck. The embryonic pharynx (which includes future oral and nasal cavities) is a much more extensive area than the adult pharynx. The main feature of the developing pharynx is a series of arches, internal pouches, and external clefts, which together comprise the pharyngeal apparatus. This structure is associated with other developing splanchna of the neck, e.g., the thyroid and parathyroid glands, tonsils, and thymus. Within each of the pharyngeal arches are the developing aortic arches and, specific for each arch, cranial nerves. The complex relations of the mesenchymal derivatives of arches (muscles, cartilage, bones) with the neurovascular bundles within each arch are presented and explained. The pharyngeal apparatus undergoes dramatic transformations: pouches and clefts disappear without interruption (interruption would produce gills and support the misnomer “branchial apparatus”). In addition, in the lateroventral neck, somites migrate to produce other muscles such as sternocleidomastoid and trapezius innervated by spinal nerves. Lateral congenital anomalies largely rely on persistence of a cleft/and or pouch or communication between the two. Their tracts have a “crooked” course among other entities generated by alterations that take place during embryogenesis.

The Effect of the Scanning Mode on the Finished Precision for SLA Technology

Stereo lithography apparatus is an advanced technology that uses photopolymers as the raw materials from which the prototypes are built. The RP manufacture system uses lasers or ultraviolet light to expose selectively the surface of the liquid resin and builds a three-dimensional part according its CAD model in a layer-by-layer manner. The absorption of energy causes photo-polymerization that changes the liquid resin into a solid, expanding the cured volume but shrinking simultaneously. The primary reason for the volume distortion and deformation of the stereo lithography apparatus part are the interlaminar stress generated by resin contraction. The volume shrinkage and curl distortion of the resin will lead to poor accuracy of the built prototype because the bending stress cannot be compensated for. Selecting a non-standard gear as experimental object and manufactured in the SCPS350B rapid prototyping machine. Four kinds of scanning mode, includes X-X mode, X-Y mode, XY mode and XY ST mode, are respectively carried out. From the results, it is found that SLA parameters, i.e. scanning mode and scanning speed significantly affect the forming precision of the prototype. The accuracy of the prototype with XYST mode is prior to the XY mode, and the X-Y mode is prior to the X-X mode. With the lower scanning speed and surface recoating process can further improve the finished precision.