Identification of common sensory features for the control of CNC milling operations under varying cutting conditions

The main focus of this study is to identify the most influential and common sensory features for the process quality characteristics in CNC milling operations—dimensional accuracy (bore size tolerance) and surface roughness—using three different material types (6061-T6 aluminum, 7075-T6 aluminum, and ANSI-4140 steel). The materials were machined on a vertical CNC mill, retrofitted with multiple sensors and data acquisition systems, to investigate the effects of variations in material types and machining parameters. The sensor data include cutting force measurements, spindle quill vibration, and acoustic emission, each of which further divided into measurable components, such as x, y, and z components in cutting force, x and y spindle quill vibration, DC, AC, and Count Rate for acoustic emission signals. Those components were filtered and analyzed to determine the sensory features that best correlate with process quality characteristics. Tool wear rate and machining characteristics appeared differently, depending on the material types, yet some components of the sensory data were found to be significant with relation to the variations in bore size and surface roughness for all three types of materials. This suggests that even under the varying cutting conditions involving different materials, the identified sensory features can be used for the reliable and accurate control of milling operations.     

A practical hole testing technique using a meter display eddy current instrument

A practical technique for the detection of cracks emanating from holes was investigated for non-ferrous materials using the eddy current method. This technique is suggested when more appropriate test equipment is not available. An unshielded absolute pencil probe and a meter display instrument were utilized in the study. It was determined that holes with a minimum diameter of 6.5 mm can be tested efficiently for the detection of cracks at least 0.15 mm deep. For the equipment used, the hole depth that can be tested is limited about 11 mm if access from the other side is not possible. The detection capability was confirmed by an impedance plane display instrument using rotary differential probes.     

Derivation of machine tool error models and error compensation procedure for three axes vertical machining center using rigid body kinematics

Volumetric positional accuracy constitutes a large portion of the total machine tool error during machining. In order to improve machine tool accuracy cost-effectively, machine tool geometric errors as well as thermally induced errors have to be characterized and predicted for error compensation. This paper presents the development of kinematic error models accounting for geometric and thermal errors in the Vertical Machining Center (VMC). The machine tool investigated is a Cincinnati Milacron Sabre 750 3 axes CNC Vertical Machining Center with open architecture controller. Using Rigid Body Kinematics and small angle approximation of the errors, each slide of the three axes vertical machining center is modeled using homogeneous coordinate transformation. By synthesizing the machine's parametric errors such as linear positioning errors, roll, pitch and yaw etc., an expression for the volumetric errors in the multi-axis machine tool is developed. The developed mathematical model is used to calculate and predict the resultant error vector at the tool–workpiece interface for error compensation.     

Impurity control in the production of boric acid from colemanite in the presence of propionic acid

The most important problem in boric acid production from colemanite ores with H₂SO₄ is the formation of MgSO₄ impurity due to the partial decomposition of clay minerals in the reaction media. Increase of MgSO₄ concentration in solution may be balanced by the discharge of mother liquor which leads to decrease the efficiency of the process. Therefore, the intake rate of MgSO₄ should be lowered for obtaining high purity product in a high yield process. In order to control the intake rate of MgSO₄ impurity, propionic acid, which does not decompose the clay minerals, is used in an acid mixture with H₂SO₄. Batch wise laboratory experiments showed that the higher the propionic acid in reacting acid mixture, the lower the magnesium intake rate. When 10% of required H₂SO₄ replaced by propionic acid, magnesium intake concentration decreased to approximately half of the value obtained in the reaction with H₂SO₄.     

Microencapsulation of Extra Virgin Olive Oil by Spray Drying: Effect of Wall Materials Composition,Process Conditions,and Emulsification Method

Food and Bioprocess Technology - The objective of the study was to investigate the microencapsulation of extra virgin olive oil by spray drying to increase its stability and application area. The...     

Impact resistance behaviour of silicone coated warp knitted spacer fabrics used for protective clothing

This paper aims to analyse the effect of coating, fabric layers and structural parameters on the impact resistance behaviour of warp knitted spacer fabrics used for protective clothing. For this purpose, six warp knitted spacer fabrics were produced by varying thickness and mesh structure and were coated with a silicone substrate. A drop-weight impact tester was used to determine the impact resistance characteristics of the samples. The results indicate that, the impact resistance properties of warp knitted spacer fabrics can be improved considerably by coating as reducing approximately 10 kN of the peak transmitted force. Also, the structural parameters such as fabric thickness and mesh structure have significant effects on impact resistance behaviour of the samples. The fabrics with higher thickness and smaller size mesh on the outer layers have better impact resistance properties. Additionally, the lamination of spacer fabrics can effectively improve the impact resistance characteristics of the spacer fabrics. The warp knitted spacer fabrics can be used as an energy absorbing material for body protection by varying their structural parameters, fabric lamination and/or by coating.     

Diagnostic value of electrical stimulation of lumbosacral roots in radiculopathies

Needle electrical stimulation of the lumbosacral roots at the laminar level of the Th12-L1 or L1-2 intervertebral spaces were performed in 24 normal subjects and 58 patients with various kinds of lumbar radiculopathy (unilateral L4, L5 and S1 herniated nucleus pulposus and lumber stenosis). The root stimulation method was compared with conventional needle EMG. Lumber electrical stimulation showed root abnormalities objectively in 80% of patients while the diagnostic value of needle EMG was 65%. Therefore, electrical root stimulation is superior to routine EMG for localizing lumbar root involvement. However, the only needle EMG demonstrated the root pathology in 7 cases (12%) and single electrophysiological abnormality was found by the root stimulation in 16 cases (27%). Thus, both electrophysiological methods should be complementary to each other in evaluation of the lumbar radioculopathy.     

Effects of MgO on the Electronic and Superconducting Properties in Succinic Acid (C4H6O4) Doped MgB2 Bulks

In this paper, we report the doping effects of succinic acid, C₄H₆O₄ (from 0 to 30 wt%) on the lattice parameter, critical temperature (T _c), critical current density (J _c), upper critical field (H _c2), and irreversibility field (H _irr) in MgB₂ superconductor. It was found that MgB₂ doped with 10 wt% C₄H₆O₄ and sintered at 900 °C exhibited excellent J _c above 10⁴ A?cm^?2 at 5 K and 8 T. Impurity scattering due to C substitution, improved crystallinity and the least amount of MgO in 10 wt% doped sample improves J _c very significantly. The MgO amount is rapidly increased in 20 and 30 wt% doped samples which causes a strong depression of J _c, H _c2, H _irr due to poor inter and intra-grain connectivity.     

Traumatic rupture of hydatid cysts: a 12-year experience from an endemic region

Adrenomedullin (AM), a potent hypotensive peptide, is produced in numerous tissues including adrenal gland, kidney, brain and pituitary gland, where it acts to modify sodium homeostasis. Central AM administration dose-dependently inhibits sodium appetite. AM antisense oligonucleotide treatment significantly lowered peptide content in the hypothalamic paraventricular (PVN) nucleus and exaggerated the consumption of sodium. These results support a physiologic role for adrenomedullin gene products in the central regulation of sodium homeostasis.