Air-jet System Research Articles

Evaluation of the grinding process utilizing an auxiliary compressed air jet on cleaning the grinding wheel surface

Grinding is one of the most complex and precise machining operations, with the performance of the grinding wheel being heavily reliant on its surface conditions. Removed chips tend to be forced back to the wheel surface due to the intense heat generated in the grinding zone. The loaded chips block the wheel's grinding capability, resulting in increased grinding force and temperature, wheel chatter, and workpiece thermal degradation. To solve these problems, this research examines the effectiveness of an auxiliary compressed air jet system during the grinding of spk tool steel with an alumina grinding wheel to clean the wheel surface of lodged chips and then the percentage of wheel loading for different tests will also be evaluated. The compressed air nozzle was examined from a variety of perspectives (0, 30, 45, and 60). Grinding with and without a cleaning system, as well as conventional cutting fluid, were also employed as comparisons. In certain output results, input parameters such as grinding wheel speed (20 m/s), cutting depth (20 m), and feed rate (100 mm/s) were maintained constant. When compared to other experiments with different cleaning nozzles, the optimal inclination angle of 45°, which allows the maximum air to reach the interface between the wheel surface and chips, removed chips by pushing them off the wheel surface. Other cleaning nozzles, such as 0°, 30°, and 60°, were less successful. The incidence angle of 45° produced the best results in terms of surface roughness, diametrical grinding wheel wear, G-ratio, tangential forces, specific energy, and wheel loading analysis. Image processing was used to detect and identify chips accumulated between abrasive grains on the wheel surface. To better understand the structure of the wheel and workpiece surface, optical and scanning electron microscopy pictures were taken and analyzed. This research adds to our understanding of the grinding wheel loading mechanism and its dynamics.

Effective mitigation of cross-contamination in classroom conditioned by intermittent air jet cooling with use of portable air cleaners

This work investigated the effect of using portable air cleaners (PACs) in a classroom ventilated by an intermittent air jet system (IAJS) for reducing the risk of cross-contamination. The classroom had two student groups separated by an aisle where the PACs were placed and operated continuously. A 3-D computational fluid dynamic (CFD) model was developed and validated experimentally to predict the complex transient flow field. The spread of contaminants from one group to another (scenario 1) and from one row to another within one group (scenario 2) was evaluated in terms of reaching concentration levels similar to the case implementing the 2-m distancing between students. Two indicators were used; the intake fraction index (iF) and an exposure reduction index (ER) that compared the proposed system to a reference case when the PAC is not used (“No-PAC”).It was found that a PAC flowrate of 350 m3/h was able to fulfill the aforementioned criteria for typical IAJS flow rate of 294 l/s and a period of 4.5 min. The proposed system reduced the exposure by 67% for the students sitting in the same group of the infected student and by 87% for the students sitting in the neighboring group compared to the “No-PAC” case. The maximum exposure level of IJAS-PAC system was lower than that obtained with seating distance of 2 m. Furthermore, it was found that operating the PAC at 350 m3/h resulted in 3% increase of the energy compared to operation of the IAJS alone.

Experimental and Numerical Research on the Formation Conditions and Entrainment Characteristics of Supercavity by Rear Jet Reflux

Aiming at better controlling the ventilated supercavity flow for drag reduction, the experimental and numerical researches of supercavity by rear gas reflux are proposed in this paper. Several experiments with different test bodies have been carried out to study the formation and collapse conditions of jet-reflux supercavity. An open-circulation water tunnel for ultra-high-speed jet experiment and air jet system is employed to form jet-reflux supercavity around the bodies installed in the forward strut. The experiment results show that the supercavity can be maintained by the reflux of tail jet flow when an initial supercavity covering the jet outlet is formed. However, the supercavity will be destroyed when the jet intensity is further enhanced. Under the same jet coefficient, the scale of jet-reflux supercavity extends as the increase of the body length, while the critical jet coefficient for the collapse of the supercavity decreases as the increase of the body length. The multiphase flow model coupling the VOF model and the level-set method is applied to capture the air-water interface. Then, the flow field characteristics of the jet-reflux supercavity are analyzed and compared with the ventilated supercavity. The streamline inside the cavity presents considerable three-dimensional asymmetry inflating flow characteristics. The variation of the gas reflux coefficient along the axial direction is obtained, which indicates that a handful of reflux gas are required to sustain the head cavity. Therefore, the jet-reflux supercavity can be formed within a certain range of the tail jet intensity. Although jet intensities are not equal to each other, the scale of cavity head is roughly maintained under the same reflux coefficient. When the supercavity gets closed to the nozzle outlet, the maximum scale of cavity is decreased, which leads to a weaker reflux at the outlet. The cavity interface will be impinged by the high-speed gas and mixture liquid, which obviously causes deformation and final collapse. In order to improve the stability of the jet-reflux supercavity, it is necessary to use the gas re-directed structure to control the reflux.

Indentation Stiffness Measurement by an Optical Coherence Tomography-Based Air-Jet Indentation System Can Reflect Type I Collagen Abundance and Organisation in Diabetic Wounds

There is a lack of quantitative and non-invasive clinical biomechanical assessment tools for diabetic foot ulcers. Our previous study reported that the indentation stiffness measured by an optical coherence tomography-based air-jet indentation system in a non-contact and non-invasive manner may reflect the tensile properties of diabetic wounds. As the tensile properties are known to be contributed by type I collagen, this study was aimed to establish the correlations between the indentation stiffness, and type I collagen abundance and organisation, in order to further justify and characterise the in vivo indentation stiffness measurement in diabetic wounds. In a male streptozotocin-induced diabetic rat model, indentation stiffness, and type I collagen abundance and organisation of excisional wounds were quantified and examined using the optical coherence tomography-based air-jet indentation system and picrosirius red polarised light microscopy, respectively, on post-wounding days 3, 5, 7, 10, 14, and 21. The results showed significant negative correlations between indentation stiffness at the wound centre, and the collagen abundance and organisation. The correlations between the indentation stiffness, as well as collagen abundance and organisation of diabetic wounds suggest that the optical coherence tomography-based air-jet indentation system can potentially be used to quantitatively and non-invasively monitor diabetic wound healing in clinical settings, clinical research or preclinical research.

Comparing double jersey knitted fabrics made of Tencel and modal yarns, spun by different spinning methods

A double-bed circular knitting machine with a gauge of E17 and a needle bar diameter of 200 mm (8 in) was used to make three groups of plain weft knitted Tencel fabrics and three groups of modal knitted fabrics. The yarns were spun using three spinning methods: ring, rotor, and air-jet system. Their count was 20 tex. All the knitted fabric samples were manufactured under the same conditions. One-half of each knitted fabric sample remained unfinished, while the other half was finished. Structure parameters of all finished and unfinished knitted fabrics were analyzed, and the most significant parameters were compared. Tensile properties of the knitted fabrics in wale and course directions were measured. The difference in the elasticity of the knitted fabric was analyzed in particular, and the portions of knitted fabric stretch are given. The basic conclusion is that using equal yarn fineness, but different raw material composition and structure, the produced knitted fabrics had substantially different fabric masses per unit area. The raw material composition and construction of the yarn, that is, the yarn manufacturing process and the spinning process produce yarns of different structures and properties that are manifested in the structure and properties of the knitted fabric. Thus, the finishing process must be specific for each raw material composition and yarn structure.

Saliva contamination effects at different application steps on bond strength of total etch two-step adhesive

Introduction: there are clinical situations in the management of cavities favorable to saliva contamination. Human saliva is a complex mixture of oral fluids and it has been showed that the protein content of the saliva is responsible for the decrease in adhesive bond strength when contamination has occurred. Objective: this study aimed to evaluate the effect of saliva contamination during different steps of application of adhesive system on bond strength of total etch two-step adhesive system. Methods: twenty-five extracted human molars were ground flat to expose occlusal dentin. The bonding system and composite resins were applied to the dentin after etching step under five conditions (n=5/group): G1: control group–no contamination; G2: etching/ contamination/dry/adhesive system application; G3: etching/contamination/wash/dry/adhesive system application; G4: etching/adhesive system application/contamination/wash/dry/adhesive system re-application; and G5: etching/adhesive system application/contamination/dry. Microtensile bond strength was tested after specimens were stored in distilled water at 37ºC for 24h. Data (mean values -μTBS) were analyzed by ANOVA one-way and Tukey tests (α=5%), respectively. Results: groups G2, G3 and G4 revealed bond strength similar to the control (G1). Group G5 showed significantly lower bond strengths than other groups (p<0.001). Conclusion: the total- etch two-step adhesive tolerated salivary contamination except when the contamination occurred after application of the bond and it was only removed with an air jet and adhesive system was not reapplied.

Computational analysis of air jet wheel deflector for aerodynamic drag reduction of road vehicle

A concept of an air jet wheel deflector is employed to reduce vehicle aerodynamic drag. The drag reduction mechanism of the air jet wheel deflector is as follow: When the vehicle’s driving speed is over than predetermined value, the air jet system injects air in the perpendicular direction to the free stream flow. This air jet acts as an air curtain, which reduces the aerodynamic drag by deflecting the free stream flow away from the tire. Feasibility study was performed using state of the art computational fluid dynamics (CFD) technique based on the lattice Boltzmann method. Fabijanic’s simple vehicle model is used for the validation of current CFD technique and numerical study of both the conventional wheel deflector and newly proposed air jet wheel deflector. Parametric studies reveal that the air jet wheel deflector system effectually reduces vehicle aerodynamic drag up to 6.4%, while conventional wheel deflector leads to slight diminishment of aerodynamic drag of 3.6%. From this finding, it can be concluded that air jet wheel deflector is a useful device to reduce aerodynamic drag of automobile.

Simulation of Airflow inside a Computer Hard Disk Drive to Develop an Impinging Air Jet Particle Detachment System for Cleaning Head Stack Assemblies

A computer hard disc drive (HDD) contains a number of mechanical components inside. One of these is the head stack assembly (HSA). This paper describes how numerical simulation was used to investigate the particle velocities and trajectories that are experienced by the HSA inside an HDD. The resulting velocity and particle trajectory information can then be used to understand the key design variables to be used to invent an effective system that cleans particles from the HSA surface prior to installation inside the drive. The HDD performance is highly sensitive to such particles. The resulting cleaning system uses impinging air jets to remove solid particulate contaminants adhering to the surfaces of the HSA. This air jet system was then evaluated using experimentation to validate that the quantity of particles, ranging in size from 0.2 to $5~\mu \text{m}$ in diameter, was effectively reduced after implementation of the new system.

Air jet impingement to reduce hot strip wave on a run-out table

Traveling stability is necessary for a hot rolled strip on a run-out table before coiling in steel mills because it affects the process efficiency and the quality of the rolled products. This study proposes an air jet impingement system to reduce the hot strip wave that occurs during tensionless travel in a run-out table before the top end of the strip reaches the coiler mandrel. The finite element method was used to examine the pressure distributions on the moving strip associated with the parameters in the air jet systems. Experiments were carried out on a pilot-scale air jet impingement system to investigate the performance. The results show that the air impingement in the moving direction effectively reduces the strip wave, and the simulated results agree with the actual measurements and observations.

Experimental evaluation of an intermittent air supply system – Part 1: Thermal comfort and ventilation efficiency measurements

Spaces with high occupancy density e.g.; classrooms, auditoriums and restaurants, provide challenges to ventilate at a lower energy use due to elevated temperatures. To meet occupants' thermal comfort requirements traditional systems use a lot of energy. Alternative ventilation strategies that optimize high air movements in the occupied zone allow human activities at elevated temperatures while attaining improve occupants' perception and acceptance of the indoor climate at a low energy use. This paper presents an experimental evaluation of a novel ventilation strategy for high occupancy spaces that provides fresh air and thermal comfort in the sitting zone through a controlled intermittent air jet system. The strategy uses ceiling mounted high momentum air jet diffusers (AJD) made from ventilation duct fitted with nozzles that generate confluent jets. The jets coalesce into a single two-dimensional jet which is directed downwards in the sitting zone. This paper presents an experimental evaluation/analysis of the proposed system with regard to ventilation efficiency and thermal comfort measurements in a classroom mockup. Results show that the system qualifies to be used as a primary ventilation system and has local air change index >1 inside the jet, and a ventilation efficiency >50%. The system also provides better thermal climate than mixing and displacement ventilation at elevated temperatures.

압축공기 분사시스템을 이용한 유류오염 해안의 효율적 정화 및 이에 따른 미생물군집분석

본 연구의 목표는 압축공기분사시스템을 이용하여 원유로 유출이 된 해안을 정화함에 있어서 그 정화효율성과 정화 전후의 총석유탄화수소(total petroleum hydrocarbon; TPH) 농도 및 미생물군집변화를 관찰함으로써 그 최적 정화과정을 이해하기 위한 기초자료를 얻고자 하는 것이다. 압축공기제트시스템을 2-5회 연속적용 시 오염지의 TPH가 약 66%까지 저감이 된 반면에 대조구인 해수를 펌핑한 경우에는 40% 정도의 저감효과가 관찰이 되었다. 압축공기의 분사 후 PCR-DGGE에 의한 미생물군집분석 결과에서는 유류분해미생물의 군집은 확인이 되지 않았다. 이는 정화에 의한 낮은 TPH 농도(약 100 mg/kg 수준, 탄소원), 처리환경에 내재적인 제한적인 질소 및 인의 농도에 기이한 것으로 판단된다. 따라서 잔여분의 유류는 에어제트시스템을 적용시 제한적 영양염류(질소 및 인 등)를 적절한 방식과 농도로 투여할 경우 거의 완전하게 제거가 가능할 것으로 사료된다. 향후 본 기술은 고농도의 유류 및 유기물로 오염된 다양한 수질환경 및 토양환경의 효율적이고 환경친화적인 정화에 활용이 될 것으로 기대된다. The objectives of this study were to investigate effectiveness of the Compressed Air Jet (CAJ) System for cleaning up shorelines contaminated with crude oils and to examine effects of the system on total petroleum hydrocarbon (TPH) removal and microbial community changes before and after remediation of the oil-contaminated shorelines. These data will lead to better understanding of optimized remediation process. About 66% of TPH reduction was observed when the contaminated site was treated with the CAJ System 2, 3, 4, and 5 times. This treatment system was more efficient than the seawater pumping system under similar treatment conditions (by 40%). By the way, little oil degrader communities were observed despite a potential function of the air jet system to stimulate aerobic oil degraders. The apparent low population density of the oil degraders might be as a result of low concentration of TPH as a carbon source and limiting nutrients such as nitrogen and phosphorus. It was proposed that the CAJ System would contribute significantly to removal of residual oils on the shorelines in combination with addition of these limiting nutrients.

In Vivo and ex Vivo Approaches to Studying the Biomechanical Properties of Healing Wounds in Rat Skin

An evaluation of wound mechanics is crucial in reflecting the wound healing status. The present study examined the biomechanical properties of healing rat skin wounds in vivo and ex vivo. Thirty male Sprague-Dawley rats, each with a 6 mm full-thickness circular punch biopsied wound at both posterior hind limbs were used. The mechanical stiffness at both the central and margins of the wound was measured repeatedly in five rats over the same wound sites to monitor the longitudinal changes over time of before wounding, and on days 0, 3, 7, 10, 14, and 21 after wounding in vivo by using an optical coherence tomography-based air-jet indentation system. Five rats were euthanized at each time point, and the biomechanical properties of the wound tissues were assessed ex vivo using a tensiometer. At the central wound bed region, the stiffness measured by the air-jet system increased significantly from day 0 (17.2%), peaked at day 7 (208.3%), and then decreased progressively until day 21 (40.2%) as compared with baseline prewounding status. The biomechanical parameters of the skin wound samples measured by the tensiometer showed a marked reduction upon wounding, then increased with time (all p < 0.05). On day 21, the ultimate tensile strength of the skin wound tissue approached 50% of the normal skin; while the stiffness of tissue recovered at a faster rate, reaching 97% of its prewounded state. Our results suggested that it took less time for healing wound tissues to recover their stiffness than their maximal strength in rat skin. The stiffness of wound tissues measured by air-jet could be an indicator for monitoring wound healing and contraction.

A Survey of Seed Cotton Dryers in Cotton Gins in the Southwestern United States

Seed cotton drying is an important and costly part of cotton ginning. Seed cotton having a moisture content above 7% cannot be cleaned or ginned properly. In this study, 73 dryers were surveyed by on-site visits in 23 gins located in the southwestern United States during the 2007 to 2010 ginning seasons. Drying systems surveyed included: standard tower, short tower, hot shelf, hi-volume tower, belt, big reel, vertical, hot air cleaner, pipe, cross-flow, hot box, hi-slip, jet, fountain, and collider systems. Forty-eight percent of dryers had the recommended dual temperature controls, while 26% had only a primary temperature control and 26% had only a maximum temperature control. Belt and big reel dryers had the lowest specific airflow rates (0.34 to 0.72 m3/kg of seed cotton) and also had the lowest energy in the conveying air (1.7 kJ/kg of lint or less). Collider, fountain, and hi-volume tower dryers had the highest specific airflow rates (1.9 to 2.8 m3/kg) and hi-slip, hi-volume tower, and standard tower dryers had the highest energy in the conveying air (7.7 kJ/kg or more). Belt, cross-flow, and hot air cleaner dryers had the lowest pressure drop across the dryer (0.5 kPa or less), while hi-slip, pipe, and standard tower dryers had the highest pressure drop (1.8 kPa or more). Fuel use was positively correlated with airflow (r=0.58) and temperature rise (r=0.59). Systems with fountain, collider, belt, big reel, jet, and hot air cleaner dryers had favorable, low values for fuel use (13.7 kJ/kg of lint or less), while systems with crossflow and hi-volume tower dryers had high values for fuel use (30.0 kJ/kg or more).

A Study on Effect of Strain Rate on Tensile Behavior of Inherent Flame Retardant Trevira CS Airjet Spun Yarns

It is well known that the tensile behaviour of a spun yarn depends largely on the caharacteristics and structural arrangements of its constituent fibres. An air-jet spun yarn consisting of a core of parallel fibres wrapped by sheath fibres, exhibits a fasciated yarn structure. Therefore, due to the marked structural differences, the responses to the tensile forces of these yarns are expected to be different. Further, the theoretical analysis of the tensile behaviour of a staple-fibre spun yarn is highly complex, mainly because of discontinuities at fibre ends. For instance, during the insertion of weft, whether by projectile or air jet, the yarn has to withstand accelerations of many thousands of times greater than that due to gravity. Hence it becomes important to understand the stress-strain responses of yarns under non-standard loading conditions vary over a range of strain rates. Hence the present paper is designed to understand the how the (Trevira CS) inherently flame retardant fibres were successfully processed on air-jet spinning system to produce 20 Ne & 30 Ne yarns. As regards the influence of high strain rate on yarn tensile characteristics, it is found that an increase in strain rate from 5 m/min to 400 m/min considerably increases the yarn tenacity but decreases the yarn breaking extension. The reduction in tenacity is significant at the 95% level of confidence in case 30 Ne pure Trevira-spun and its blended yarns. This paper is written to understand the effect of strain rate on the tensile behaviour of Trevira CS fibre.

The Angle Effects of Air Jet System on Smoke Prevention Performance in a Building Fire

The Angle Effects of Air Jet System on Smoke Prevention Performance in a Building Fire

A novel noncontact method to assess the biomechanical properties of wound tissue

A novel noncontact optical coherence tomography based air-jet indentation system was developed for characterizing the biomechanical properties of soft tissue in a noncontact way. This study aimed to measure the stiffness of diabetic foot ulcer tissues by using this air-jet indentation system, and examining the test/retest reliability. Eight subjects with diabetes (seven males, one female), with a total of 10 foot ulcers between them, participated in the study. A total of 20 measuring sites located at the central wound bed (n=10) or peri-ulcer areas (n=10), respectively, were evaluated with the air-jet indentation system. Four cycles of loading and unloading, each with a duration of approximately 36 seconds at an indentation rate of 0.08 mm/s, were carried out for each indentation trial. The test/retest reliability was examined at all measuring points. The average stiffness coefficient of the peri-ulcer area (mean ± SD: 0.47 ± 0.15 N/mm) was significantly larger than that of the central wound bed area (mean ± SD: 0.35 ± 0.23 N/mm; p=0.042). A high value for test/retest reliability was shown (intraclass correlation coefficient: 0.986; Pearson's correlation: r=0.972, p<0.001). Our preliminary findings showed that the peri-ulcer area had greater stiffness than the central wound bed. This greater magnitude of hardness and inelasticity at the peri-ulcer region may scatter part of the contractile forces for wound contraction during the healing process. We found the novel air-jet system to be a reliable tool for characterizing the stiffness of soft tissues around the wound in a noncontact way.

Xenograft of free or microencapsulated sertoli cells as a potential therapy for experimental Type 2 Diabetes Mellitus

Introduction and Aim . Type 2 Diabetes Mellitus (T2DM), one of the world’s most important, common and costly diseases associated with devastating complications, is caused by insulin resistance mainly due to a chronic inflammation of the visceral adipose tissue with local and systemic increases in proinflammatory cytokines and adipokines such as tumor necrosis factor-α (TNF-α) and IL-6. Sertoli cells (SC), considered mere mechanical cell aids, have been recently revisited with respect to their functional competence showing that these cells may provide immunomodulatory and trophic factors that are able to ameliorate survival and development of different cell types and constitute an immuno-protective shield for transplantation in many diseases such as Type 1 Diabetes Mellitus. Aim of this work was to verify if the injection of free (subcutaneously) or microencapsulated (intraperitoneally) SC would reverse hyperglycaemia in db/db mice spontaneous T2DM Materials and Methods . Porcine pre-pubertal SC were isolated, according to previously established methods, after finely chopping the retrieval testicles, with double enzymatic digestion with Collagenase P and a mixed solution of trypsin and DNase I. SC enveloped in Barium alginate-based microcapsules (Ba-SCMCs) were prepared according to our method, by a mono air-jet device system. Free SC and Ba-SCMCs were examined as far as: (a) SC morphology by light microscopy; (b) SC viability, by fluorescence microscopy after staining with ethidium bromide and fluorescein diacetate; (c) SC in vitro function (α-aromatase activity and IGF-I secretion); (d) reversal of T2DM in spontaneous diabetes db/db mice, were concerned. Results . Ba-SCMCs showed excellent features in terms of size, morphology, sphericity and coalescence. SC viability, both in free and microencapsulated SC, was very high (over 90%). Very good α-aromatase activity and IGF-I secretion were associated with the examined SC preparations. Both subcutaneous free SC injection and intraperitoneal transplantation of Ba-SCMCs demonstrated a significant reduction, in 60% of the treated mice, of HbA1c (6.6 % vs 8.8 %) with a normalization of intraperitoneal glucose tolerance test. Conclusions . SC may be enveloped in Ba-SCMCs with no loss of their functional properties and morphology. Xenograft of SC, both free and enveloped in barium alginate microcapsules, induced an important reduction of HbA1c blood levels with a normalization of glucose tolerance test (IPGTT). This result might open new perspectives for the future therapy of human T2DM.

Nondominant arm advantages in load compensation during rapid elbow joint movements.

This study was designed to examine interlimb asymmetries in responding to unpredictable changes in inertial loads, which have implications for our understanding of the neural mechanisms underlying handedness. Subjects made repetitive single joint speed constrained 20 degrees elbow flexion movements, while the arm was supported on a horizontal, frictionless, air-jet system. On random trials, a 2-kg mass was attached to the arm splint prior to the "go" signal. Subjects were not given explicit information about the mass prior to movement nor were they able to view their limb or the mass. Accordingly, muscle activity, recorded prior to peak tangential finger acceleration, was the same for loaded and baseline trials. After this point, substantial changes in muscle activity occurred. In both limbs, the load compensation response was associated with a reduction in extensor muscle activity, resulting in a prolonged flexion phase of motion. For the nondominant arm, this resulted in effective load compensation, such that no differences in final position accuracy occurred between loaded and baseline trials. However, the dominant arm response also included a considerable increase in flexor muscle activity. This substantially prolonged the flexor acceleration phase of motion, relative to that of the nondominant arm. As a result, the dominant arm overcompensated the effects of the load, producing a large and systematic overshoot of final position. These results indicate more effective load compensation responses for the nondominant arm; supporting a specialized role of the nondominant arm/hemisphere system in sensory feedback mediated error correction mechanisms. The results also suggest that specialization of the dominant arm system for controlling limb and task dynamics is specifically related to feedforward control mechanisms.

窒化チタンインク特性がインクジェット印刷に与える影響

20 vol% titanium nitride ink was prepared, and printed directly by ink jet printing. The effect of the ink characteristics was studied on both printing and forming behaviors. An ink jet printer of the air jet system was employed which could eject high viscosity ink. In order to improve the stability of the ink, poly carboxyl ammonium (PCA) and microcrystalline cellulose (MC) were found to be the proper additives to the suspension. As a result, it was possible to prepare the ink with various characteristics by adding PCA and MC. The control of the ink characteristics was found to be the key concept in adjusting printing ejection and compact characteristics. As the apparent viscosity of the ink increases, the weight of printing ejection decreased, and the thickness of printed compact also thinned.

Effects of altering initial position on movement direction and extent.

The purpose of this study was to examine the relative influence of initial hand location on the direction and extent of planar reaching movements. Subjects performed a horizontal-plane reaching task with the dominant arm supported above a table top by a frictionless air-jet system. A start circle and a target were reflected from a horizontal projection screen onto a horizontally positioned mirror, which blocked the subject's view of the arm. A cursor, representing either actual or virtual finger location, was only displayed between each trial to allow subjects to position the cursor in the start circle. Prior to occasional "probe trials," we changed the start location of the finger relative to the cursor. Subjects reported being unaware of the discrepancy between cursor and finger. Our results indicate that regardless of initial hand location, subjects did not alter the direction of movement. However, movement distance was systematically adjusted in accord with the baseline target position. Thus when the hand start position was perpendicularly displaced relative to the target direction, neither the direction nor the extent of movement varied relative to that of baseline. However, when the hand was displaced along the target direction, either anterior or posterior, movements were made in the same direction as baseline trials but were shortened or lengthened, respectively. This effect was asymmetrical such that movements from anterior displaced positions showed greater distance adjustment than those from posterior displaced positions. Inverse dynamic analysis revealed substantial changes in elbow and shoulder muscle torque strategies for both right/left and anterior/posterior pairs of displacements. In the case of right/left displacements, such changes in muscle torque compensated changes in limb configuration such that movements were made in the same direction and to the same extent as baseline trials. Our results support the hypothesis that movement direction is specified relative to an origin at the current location of the hand. Movement extent, on the other hand, appears to be affected by the workspace learned during baseline movement experience.