• A Heuristic to Reduce the Maximum Work-in-Process for Aircraft Maintenance

      Verhine, Harrison Mikeal; School of Engineering
      Air Logistics Complexes (ALCs) provide depot maintenance for aircraft fleets for the United States Air Force (USAF). The rate at which aircraft are inducted into maintenance is in constant flux. For example, initiation of new modification programs, aging aircraft fleets, and demand for new work all impact future workload requirements and planning. The induction schedule identifies the dates that aircraft arrive at a maintenance depot. A good induction schedule can help minimize flow days (time an aircraft is in maintenance) while a poor induction schedule can result in increased work-in-process (WIP) and long aircraft maintenance queues. Depot maintenance can be modeled as a job shop scheduling problem. Many heuristics and metaheuristics have been proposed to solve variations of job shop problems. This paper utilizes a simulation tool, RAMP, which was developed to simulate the maintenance performed on aircraft and produces results about the utilization, queue lengths, and other performance metrics of the system. This thesis describes a developed heuristic, which is used to alter induction schedules in order to smooth WIP curves and reduce queue times. The algorithm keeps most of the induction schedule un-altered by manipulating induction dates for a relative few aircraft around important times in the simulation, namely around large extrema. The algorithm uses a numerical derivative and an application of the second derivative test to detect important extrema. Once these extrema are identified, it attempts to reduce aircraft WIP around peaks and fill aircraft WIP into valleys. This is performed by shifting the induction dates of aircraft around those extrema. The algorithm was successful in reducing the maximum WIP for 12 out of 16 schedules tested. Of the successful runs, there was an average improvement of 8.7% on maximum WIP. Performance of the heuristic is dependent on the parameters used; however, modifications were made to mitigate this dependence. The algorithm can function well in its current version; however, there is still additional work that can be done to further increase performance.
    • A Novel Design Of A Hip Brace Mechanism For Rehabilitation Of Limited Range Of Motion

      Leslie, Morgan
      Osteoarthritis (OA) and femoroacetabular impingement (FAI) are both conditions that can cause destruction of the hip joint – resulting in pain, limited range of motion, and gait imbalances. The purpose of this study is to analyze the gait and muscle activity in patients with OA and FAI and propose and test the effectiveness of a rehabilitative mechanism that aims to help balance muscle activity to improve gait. Each of the three subjects (one baseline, one with FAI, and one with OA) underwent electromyographic (EMG) analysis and 2-D gait analysis for three conditions: with no brace, with just the brace, and with the mechanism. The FAI subject showed low peak gluteal activity in the affected side compared to the unaffected (14.70% less affected gluteus medius (GMD), 11.77% less affected gluteus maximus (GMX)). The device increased GMD activity on the affected side to be closer to that of the unaffected side at 5.5% less. The GMX peak activity increased by 21.83%, even though the affected side was still less by 11.51%. The OA subject showed higher mean gluteal activity on the affected side when compared to the unaffected side. The GMD and GMX activity was 9.6% and 0 7% greater, respectively. With the device added, the GMD and GMX means on the affected side was 13.6% and 0.7% greater, respectively. The subject with FAI showed at 14.57o less hip range of motion (ROM) on the affected side when compared to the baseline value of 50o. When the device added, the ROM decreased further by 1.79o. The FAI subject showed 2.42o more pelvis ROM than that of the baseline subject. With the device, the difference between the FAI subject and the baseline subject was only 0.61o. The OA subject showed a percent difference less of 33.06% between his double step length on the affected side and the normal value of 1.41 m. With the device, the percent difference less becomes 29.27%. With no brace or device, this subject shows 7.7% less time in stance phase than the normal value of 60% and only 0.83% more when the device is worn. Finite element analysis (FEA) was conducted to determine the mechanical integrity and fatigue life of the mechanism and free body diagrams (FBDs) with calculations were done to estimate the change in muscular forces with the mechanism. The FEA found a maximum stress of 32.51 ksi. The margin of safety for fatigue of an unnotched condition was calculated to be 2.46. In a notched case, the cycles until failure was determined to be 213,797 cycles. The FBDs found that there is a muscle activity increase of 4.3% and 2.6% for extension and flexion, respectively. Future studies would need to be done with a larger pool of subjects, different design ideas (to optimize results), and trials done after the subjects have used the device for a time.
    • A Novel Design of a Knee Brace for Patients with Spinocerebellar Ataxia: A Comparative Study

      Speece, Brooke; School of Engineering
      Spinocerebellar ataxia (SCA) is an inherited degenerative disease of the central nervous system leading to the deterioration of the cerebellum, the voluntary motor control center of the brain. Patients with SCA are unable to maintain balance and normal posture and have an ataxic gait, resulting in increased abnormalities in gait parameters. Some patients may increase muscle co-activation to provide stability during gait by stiffening their joints. A compensation that typically results in reduced joint range of motion and a decrease of gait parameters. The subject of this study is a 47-year-old female with spinocerebellar ataxia type 2 and presents with difficulty standing, abnormal ataxic gait, and poor balance. The purpose of this study was to design and construct a brace to provide stability and aid the patient in walking as well as standing and sitting. Two braces were designed, constructed, and tested to compare the efficacy of each: a tension brace with an adjustable Velcro tension band attachment on the anterior portion of the brace and a spring brace with a torsional spring and 3D printed housing attached to the brace knee joint. Electromyography analysis determined the knee antagonist co-activation index (CAI) increased by 86.3% during stance and by 168.7% during swing with the spring brace, indicating greater stability and motor control. The tension brace had little to no effect on CAI. During standing, the tension brace increased quadriceps activity by 65.4% and the spring brace increased activity by 37.2%, indicating both braces could help to rehabilitate weak muscle function. Joint angle diagrams obtained in the gait analysis determined both braces aid the knee during the terminal stance and pre-swing. With the spring brace, cadence increased by 8.7% (72.4 steps/min) and velocity by 8% (0.53 m/s), while the tension brace increased cadence 4.9% (69.7 steps/min) and velocity remained unchanged. The F-Scan pressure analysis determined the spring brace decreases abnormal peak force during loading which can indicate balance problems at heel strike. The patient preferred using the spring brace to the tension brace. She felt it provided her more stability and speed and elected to keep the brace after testing.
    • Ankle Foot Orthosis Designs For Patient With Peroneal Nerve Damage: The Comparison Of Three Devices For Their Effectiveness In Rehabilitation

      Cai, Huan Huan
      The study involves the participation of a patient with peroneal nerve damage. The injury caused him to be unable to dorsiflex the ankle joint. His pathological gait symptoms were investigated using 2D gait motion test. The study evaluates the functionalities of three different ankle foot orthoses. Device 1 is immovable and allows no joint motions of the ankle. Device 2 allows plantarflexion and dorsiflexion motions of the ankle. Device 3 provides the same degree of freedom as device 2 with greater assistances for dorsiflexion. The first two devices are currently available in clinical practice. The goal of this research is to design and test a rehabilitation device that can help the patient to recover. Also, to determine that the device 3 is more effective than the other two. Gait motion data was recorded from two movement planes, frontal and sagittal. The results are composed of data from four different aspects: duration, cadence, range of motion, and sagittal plane gait motions. Also, there are four data collection phases, N1 to N4, for all four aspects of data. N1 is the stage before using the devices. N2 is after using the device 1, and N3 is after using the device 2, so on for N4. The range of motion results show that after using the device 1 and 2, the dorsiflexion degree decreased by -3.97° and -1.49°, respectively. For device 3, it increased by 1.67°, which implies that the device 3 can enlarge the dorsiflexion range, as opposed to the other two. The cadence data are as following: 1455, 1399, 1373, and 1348 steps/km, in the order of N1 to N4. The data demonstrates a decreasing trend, which means that the walking performances are becoming more efficient, and they are the best when using device 3. Sagittal plane gait motion data show the raw performances of the dorsiflexing muscles without wearing the devices. The analysis compares the total left ankle dorsiflexion degrees. They are listed as the following in the order of N1 to N4: -124.27°, -167.00°, -107.69°, and -62.63°. The closer the values are to zero, the greater the dorsiflexion degree. N4 has the greatest dorsiflexion degree, which indicates that the device 3 is able to strengthen the dorsiflexors more effectively than the other two.
    • Biomechanical Evaluation Of Hybrid, Bicortical And Univrotical, Screw Configurations For Internal Bone Late Fixation Of Long Bone Fracture : An In-vitro Study Of Porcine Femur Bone Models / By Gabriel Jonas Gonzalez Quintero.

      Gonzalez Quintero, Gabriel Jonas
      ABSTRACT Midshaft fractures of the femur are commonly seen in clinical cases. A fracture is a break through the bone that compromises bone stability and its surroundings. After a fracture, the bone must go through bone healing to recover its full stability and function. Internal bone plate fixation of midshaft femur fractures is one of the leading ways that surgeons treat transverse fractures of the femur bone. The purpose of the implant plate is to provide structure and stability while the bone regenerates. Current clinical applications prefer the use of 6 bicortical non-locking screws in a 7 hole dynamic compression plate, considered as the traditional method, for the internal fixation of midshaft femur transverse fractures. This configuration provides a secure structure to allow for long-term rehabilitation, but it is also very invasive to the bone. The traditional method does not necessarily provide the best mechanical performance possible. This study proposes the use of hybrid configurations of screws for an alternative method of the bone plate fixation. Hypothetically, the combinations combine 4 unicortical and 2 bicortical screws into the plate/screw to bone interface to provide a balance between level of support and invasiveness offered by the implant. The goal of this study is to conduct an in-vitro, a physical, and a statistical analysis to better understand the implications of the hybrid configurations and compare their performance to the traditional method. The overall purpose of this study is to identify the best configuration of bone plate fixation for rehabilitation of a fractured femur bone. The study was conducted using porcine femur models. Porcine femurs are known to be anatomically and mechanically similar to the human femur [31]. Four groups were considered for this study. The control group was based on the traditional method of bone plate fixation, consisting of 6 bicortical screws. Each of the three testing groups had four unicortical and two bicortical screws, each with a different placement for the bicortical screws. The bicortical screws for Groups 2, 3, and 4 were located in the innermost, middle, and outermost holes of the plate, respectively. Seven bone samples were made for each group (n=7) following the same procedure of bone plate fixation for each group. A 10 mm transverse fracture was created at the midshaft of the femur to simulate the fractured bone. Each sample was then fixated at both ends of the femur through an epoxy. All bones were tested on the Materials Testing System located in the orthopedics lab of Mercer University, School of Engineering. Three analyses were conducted to test the performance of each configuration: an experimental in-vitro analysis of mechanical properties, a theoretical analysis of force interactions, and a statistical analysis for of significant difference of the data. The in-vitro investigation was done through a material analysis of the construct. Axial compression and axial failure tests were implemented to simulate the mechanical behavior of the construct under elastic and plastic deformation. In the axial failure test, pre- and post-cyclic assessments were made and the axial stiffness was calculated for each group. The average axial pre-stiffness was 909 ± 117 N/mm for Group 1 (the control group), 958 ± 104 N/mm for Group 2, 1083 ± 287 N/mm for Group 3, and 1096 ± 445 N/mm for Group 4. Overall, the configurations were ranked based on pre-stiffness performance in the following order: Group 4 > Group 3 > Group 2 > Group 1. The average axial post-stiffness was 1181 ± 156 N/mm for Group 1, 1046 ± 162 N/mm for Group 2, 1160 ± 207 N/mm for Group 3, and 1240 ± 521 N/mm for Group 4. Overall, the configurations were ranked based on post-stiffness performance in the following order: Group 4 > Group 1 > Group 3 > Group 2. The average axial stiffness was 407 ± 145 N/mm for Group 1 (the control group), 445 ± 91 N/mm for Group 2, 460 ± 143 N/mm for Group 3, and 680 ± 225 N/mm for Group 4. The average axial yield strength was 3910.13 ± 1776.638 N for Group 1 (the control group), 4268 ± 1837 N for Group 2, 5107 ± 2608 N for Group 3, and 7002 ± 2187 N for Group 4. The average ultimate failure force was 4949 ± 2678 N for Group 1 (the control group), 5743 ± 3026 N for Group 2, 6065 ± 3052 N for Group 3, and 8499 ± 1492 N for Group 4. Overall, the configurations were ranked based on the axial failure performance in this order: Group 4 > Group 3 > Group 2 > Group 1. The theoretical analysis studied the forces and moments acting on the implant to bone interface. This analysis was done through the use of free body diagrams. An analysis was performed for both the static (in equilibrium) and dynamic (not in equilibrium) behaviors of each configuration. From the static analysis it was determined that bicortical screws create larger forces on the bone than unicortical screws. The presence of more bicortical screws can result in higher wearing for the bone, as the bone cortex must create counteracting forces under axial loading. Thus, more bicortical screws results in higher bone wear at the implant interface. From the dynamic analysis it was concluded that if bicortical screws are placed farther from the fracture gap, they are able to provide a higher stiffness for the system due to a greater moment arm from the bicortical screw to the fracture gap. Based on these results, Group 4 represents a better theoretical model than Groups 1, 2, and 3. The statistical analysis was done through Minitab 17. The groups were tested for distribution normality and statistical significance in each of the variables. Most groups presented a normal distribution of the data. A total of 4 cases came out to be non-normally distributed, which only meant that these cases were not able undergo the statistical significance test. ANOVA analysis was done for those cases that presented a normally distributed data. Most variables presented no statistically significant difference between the groups. However, there were two cases, the axial stiffness under equal variances and the ultimate failure force under unequal variances, that had a p-value lower than 0.05. For these two variables there was enough evidence to show that the values were statistically significantly different and these were not attributed to chance. The material and physical analyses agreed with each other on the conclusions made. Overall, it was found that Group 4 offers a less invasive model than Group 1 and also greater stability and resistance to deformation than Groups 1, 2, and 3. In addition, the statistical analysis gave evidence that certain variables do represent the actual averages of the overall population. In conclusion, this study recommends the use of Group 4’s configuration as a more suitable implant for rehabilitation purposes of midshaft transverse fracture of femur bone. Keywords: DCP, Transverse Fracture, Femur Bone, Internal Fixation, Bone Plate, Unicortical and Bicortical Screw, Stiffness, Elastic and Plastic Deformation, and Configuration.
    • Choke Inductors in RF Phantom Circuit

      Radi, Amjad; School of Engineering
      This research work provides examples of how different inductors can be used for RF isolation in a range of circuits from relatively narrow band applications like portable devices up to broadband networks for data distribution. The different types of inductors used in these applications are identified and discussed. As an RF circuit designer choosing RF inductor choke might become a challenge, as this inductor is critical to get the desired signal from the antenna to get received to get processed and deny the undesired one from passing through. Common choke type are the ones used for common applications such as radio reception (FM and AM), modern digital radio reception (XM and DAB) and GPS. A failure of choosing this RF choke can cause the loss of the desired signal, increasing noise level and therefore failure of design. In this research work, the author would experiment, discuss and show results for choke inductors used for 100MHz which is used for FM reception and 220MHz which is used for DAB radio.
    • Comparative Analysis Of Two Prosthetic Foot Designs Using Cyclical Load Testing And Cad Simulation

      Haislip, Tyler
      ABSTRACT COMPARATIVE ANALYSIS OF TWO PROSTHETIC FOOT DESIGNS USING CYCLICAL LOAD TESTING AND CAD SIMULATION Under the direction of Dr. Ha Vo One major obstacle in developing lower limb prostheses is the complexity of the ankle complex. The purpose of this study is to test an old prosthetic foot, which provides stability but little movement, and a modified design that sacrifices some stability for improved range of motion at the ankle. To stay within Mercer’s international mission of low-cost prostheses, the design must be entirely mechanical in operation and comprised of easily accessible materials. Both the previous C-Shape model and the new “Spring-Foot�? model were fabricated using conventional tools in the College of Engineering machine shop and prosthetic lab. The feet were fatigue tested in an MTS system for 75,000 cycles to simulate walking for one month. C-Shape axial displacement values increased from 2mm at the beginning to 3mm at the end. The Spring-Foot had an initial max displacement of 0.6mm and ended with 0.9mm. Pre-load results from the MTS test were compared against theoretical and ANSYS values. The theoretical and ANSYS values of 231 and 250 N were close while the MTS pre-load of 600 N suggests that there were factors missed in the simulation. ANSYS Static Structural Analysis was used to compare the aluminum loading block with a polypropylene alternative under high loading conditions. Differences in vertical deformation of the two blocks were negligible, reaching only 1 mm under extreme conditions. Solidworks simulation was used to fatigue test the springs for a set displacement to compare to the MTS results. The results proved inconclusive, with the interior coils of the spring surpassing the yield stress of the material. A locked-ankle walking test was generated qualitative feedback as well as pressure and force values through MatScan software. Neither foot had a normal walking pattern, with the peak forces registering 750 N in the C-Shape stance and 650 N in the Spring-Foot stance. Lastly, a formula was derived for future spring selection with varying patient weight. Improving the realism of the testing conditions and creating more secure spring connections will yield more relevant feedback and will better showcase the effect of daily cyclical loading on the plastic pieces and spring connections.
    • Effects Of Q-angle On Lower Extremity Biomechanics And Injuries In Female Collegiate Track And Field Athletes

      Ham, Myranda Hope
      The purpose of this study is to investigate the effect that quadriceps angle, or Q-angle, has on lower extremity biomechanics in female collegiate track and field athletes, and in turn, investigate the effect that Q-angle has on the incidence of sports-related injury. Twenty members of the Mercer University Women’s Track and Field team were asked to participate in this study. Each subject’s limb length and Q-angle were measured and 2D gait analysis was performed in the Mercer Biomechanics and Gait Lab. Then, electromyographic (EMG) analysis was performed on eleven of the subjects on one of the university’s intramural fields. Each subject was also asked to provide a full history of sports injuries they had previously sustained. For data analysis, the subjects were divided into three groups based on Q-angle (group 1: 10�?�-14�?�, group 2: 15�?�-17�?�, and group 3: 18�?�+). Statistical analysis was performed using t-tests and Mood’s median tests to compare the three groups. Subjects from group 1 were found to have a lower angle hip adduction (p=0.002 compared to group 2 and p=0.05 compared to group 3) in the left frontal plane at initial contact and high incidence of shin splints (66.67%) and ankle sprains (33.33%). Subjects from group 2 were found to have larger range of motion of the knee in the sagittal plane (p=0.021 compared to group 1) and higher incidence of hamstring strains (50%). Subjects from group 3 were found to have high incidence of shin splints (50%) and injuries to the knee (26.67%). Although no statistical significance was found in the EMG data, meaningful trends were observed. Muscle activity in the vastus lateralis, rectus femoris, and lateral gastrocnemius was found to increase as Q-angle decreased. In the future, this study could be done with a higher sample size so more firm conclusions could be drawn.
    • Effects of Weathering Cycles on the Mechanical Properties of Thermoplastic Polyurethane

      Pickren, Darren Brantley; School of Engineering
      In the present work, a method for synthesizing pure thermoplastic polyurethane (TPU) and TPU composite test specimens was developed to show stress-stretch dependency, to observe the effects of weathering on samples, and to show the potential of TPU as a superior coating agent over traditional polyurethane in aerospace applications. The TPU specimens were tensile tested using ASTM standards to extremely high deformations: stretch values of 5 times original length in tensile testing. During testing, TPU specimens exhibited typical behavior of nonlinear viscoelastic materials with extensive energy dissipation during stretch-release cycles. A portion of the tested samples were exposed to 168 hours of UV radiation, moisture, and temperature fluctuation to simulate accelerated weathering and exposure to harsh environments. When comparing weathered TPU samples to non-weathered TPU samples, there was no appreciable difference in the mechanical properties or the amount of energy absorbed during deformation; the stretch-stress curves were nearly identical before and after weathering. When returned to a zero-stress state, considerable residual strain remained in all specimens. It is conjectured that strain-induced crystallization is responsible for the unique shape-memory effect that the TPU specimens experience. Slower loading rates with the same peak stretch values showed higher peak stresses in samples from the same batch, showing that the rate of crystallization is dependent upon the rate at which TPU samples are deformed. The same tests were performed with TPU composites, filled with molybdenum disulfide. While TPU composites have slightly different overall mechanical properties from pure TPU, the exposure to weathering also had minimal effect on mechanical properties of composite specimens. Fracture tests were also performed on pure TPU and composite TPU samples. The effect of UV weathering on fracture toughness of pure TPU and TPU composites is more prevalent, as specimens were hardened and their abilities to absorb energy during crack growth was greatly reduced.
    • The Effect Of Unilaterally Added Mass To The Legs On Able-bodied Gait: Implications On Heavy Prosthesis Design

      Gracyalny, Justin Thomas
      ABSTRACT JUSTIN THOMAS GRACYALNY THE EFFECT OF UNILATERALLY ADDED MASS TO THE LEGS ON ABLE-BODIED GAIT: IMPLICATIONS ON HEAVY PROSTHESIS DESIGN (Under the direction of Dr. Ha Van Vo, Ph.D., MD, DPM) INTRODUCTION: General consensus is that lighter prostheses designs reduce gait deviations and improve energy efficiency; however, these studies have not been able to provide conclusive evidence on the overall effects of different mass distributions, particularly when heavier protheses are involved. METHODOLOGY: Several components of gait mechanics including sagittal and frontal plane joint kinematics, ground reaction forces (GRFs), and relative hamstring energy expenditure (RHEE) were evaluated in able-bodied subjects with unilaterally added mass to the legs simulating a best-case scenario for heavy transtibial and transfemoral prosthesis wearers. Five- and ten-pound masses were added unilaterally to the shank and/or thigh of 10 below-knee (i.e., calf-only) subjects (Baseline, 5lb, and 10lb groups) and 11 above-knee (i.e., calf and thigh) subjects (Baseline, 5lb/5lb and 5lb/10lb groups). RESULTS: Significant differences between weight conditions (p<0.05) were found in self-selected walking speed, cadence, swing time, and stance time. Significant decreases in knee flexion during mid-swing and hip flexion during terminal swing and increases in hip extension during pre-swing were observed with increasing weight. Trunk flexion was found to increase throughout the gait cycle while decreased contralateral trunk lean was found during swing phase of the weighted limb. Relative locations of maximum and minimum joint angles were less affected, and differences were generally not statistically significant. Weighted limb GRF curves generally showed decreased maximum heel strike and toe-off forces with a less defined mid-stance. RHEE was found to increase with heavier loads and was found to increase more with distal loading. DISCUSSION: Findings agree with previous studies regarding the recommendation to avoid distal loading unless other patient benefits are gained. Findings also support idea of kinematically invariant adaptions to gait for mass perturbations. Results suggest increased muscle activity in the lumbar spine with increasing weight with potential links to lower back. Further investigation into this linkage is suggested for future studies. Finally, findings suggest additional unilateral mass plays a significant role on gait and should be avoided when possible. CONCLUSION: This study shows that unilaterally added mass plays a significant role on able-bodied gait mechanics and can be used to support and provide insight for future prosthesis design.
    • The Study Of The Properties Of Polymeric Materials Both Pristine And Coated With Metallic Nano-layers With Regard To Impact Erosion

      Culp, John Kevin
      This project will examine the impact erosion behaviors of a variety of composites and polymer materials, as well as the effect of factors such as additives and thin film coatings on the polymers and composites. The materials to be examined will be: Polycarbonate, Polypropylene, Polyethylene, Polystyrene, PVC, and Epoxy resin. Samples of each of these six materials will be subjected to Rockwell hardness tests, three-point bending tests, and solid particle erosion tests at a normal impact angle with the goal to ascertain the behavior of these materials in regards to erosion. Additionally, samples of certain materials will be coated with a thin film layer of copper, titanium, or titanium nitride by the method of DC magnetron sputtering. The coated samples will also be subjected to erosion tests to determine the effectiveness of the coatings in improving the characteristics of erosion.
    • Using Facial Features to Produce an Augmented Reality System

      Sharma, Pragya; School of Engineering
      Under the direction of Anthony Choi, Ph.D. In the following work, an augmented reality system is proposed that takes the gaze of the eye, along with facial movements for assistance, as an input to allow the user to interact with a sample menu from a restaurant. Currently, the only way for a customer to order food at a restaurant is by touching a menu in person or by having the customer touch a screen. In either instance, the customer is having to interact with surfaces that are shared by many individuals, with the risk of contracting any number of illnesses. Such is a bigger problem when it comes to living through a pandemic, for instance, where interaction between shared surfaces poses a higher risk of exposure to the virus. Using an already trained neural network that incorporates pre-identified facial landmarks that every user possesses, the program can keep track of the user’s gaze and show the positions of both the left and right pupils, respectively. Along with this, the program begins with the user opening their mouth to pass a certain threshold and starts to read input. The user guides the cursor with the movement of their face within the green box shown on screen. By stopping facial movement, the user can select a menu item with the wink of their left eye. While conducting tests to see if the program was displaying correct coordinates, user testing took place and it was found that nine times out of ten, the program was displaying the correct coordinates. With more practice, the user was able to get used to using their facial movements to guide the cursor, although the cursor control speed could be better adjusted for future testing. Along with this, such exaggeration of facial movements could be adjusted so that the user does not feel awkward utilizing the system.
    • Water Purification And Antibacterial Effects Of Metallic Nanoparticles Deposited Using Dc High Vacuum Magnetron Sputtering On Filtering Materials

      Le, Khang Nguyen
      Water and water purification is an important problem that is confronting our generation at a global level. Our research tested the antibacterial effects of Silver, Copper, Titanium, Zirconium and Aluminum metallic nanoparticles deposited on microsize filtration materials. The DC High Vacuum Magnetron Sputtering Equipment was used for the deposition of metallic nanoparticles. The thickness of the coatings was in-situ monitored using a quartz crystal microbalance and ex-situ evaluated using a profilometer. The chemical composition of the structures was characterized using the X-Ray diffraction analysis and their surface morphology was investigated using digital optical microscopy and scanning electron microscopy. Each metallic material was deposited on 3M filter paper with different thicknesses. The antibacterial effect was tested were using mBlue-E.coli 24 media, the membrane filtering technique, and an incubator which was set at 35 Celsius degrees, according to standardized methods for the examination of water and wastewater. The testing media containing the bacterial samples was contaminated water collected from the wastewater basins. The water was initially tested for the bacterial content as collected and then exposed to metallic deposited filtering materials; the remaining targeted bacteria was quantified. The antibacterial effects of metallic nanoparticles were observed and analyzed. Deactivation rates for fecal coliform and Escherichia coli were measured for different metals with varying metallic thickness coatings. All metallic nanoparticles showed a good adhesion at microscopic level to water filter paper as observed by digital microscopy and scanning electron microscopy examination. Titanium nanoparticles did not have antibacterial effect showing no change in time evolution of E. Coli and Total Coliforms as well as control samples. Zirconium and Aluminum nanoparticles had some antibacterial effect showing a small change in time evolution of E. Coli and Total Coliforms for the control and coated samples. Silver and copper nanoparticles coated filters gradually removed both E. Coli and Total Coliforms. Various thickness of silver and copper nanoparticles coated filters were investigated, and it was observed that the thickness of coatings does not have significant impact on their antibacterial activity. Additionally, this research is investigating the synergistic antibacterial effect obtained by using silver and copper thin films deposited on water filter paper and the effect of the potential applied to the electrically conductive structures. It was observed that silver nanoparticles had high antibacterial effects when a high power is applied to its conductive structures.
    • Water Quality At Mountain Springs Used For Drinking Water In The El Cercado Area, Dominican Republic

      Resto-Fernandez, Monica Cristina
      Globally, many hundreds of millions of people living in developing rural mountainous areas are believed to lack access to a safely managed drinking water source. Typically, this population subset is sustained by groundwater emerging at mountain springs, which previous studies in three different world regions have found to be commonly contaminated with E. coli. The presented research focuses on water quality of mountain springs in a rural area of western Dominican Republic. Initial preliminary investigations established understanding of study-area-wide topography and geography. Thirty-seven mountain springs throughout the study area were assessed qualitatively (for land use, geology, infrastructure, and biota) and quantitatively (for pH, temperature, electrical conductance [EC], total dissolved solids [TDS], nitrate, alkalinity, and E. coli) at 109 sampling points during three field research trips in 2017 and 2018. The study area is comprised of a high percentage of developed and agropastoral land. The mountains which surround the study area are underlain by highly fractured carbonate rock. A majority of springs were located near or in a river/streambed and had up-slope agropastoral land. Generally, a decrease in elevation of mountain springs was related to a decrease in water pH, and an increase in temperature, EC, TDS, and alkalinity for springs in the same general mountain area. E. coli concentrations of emerging groundwater were compared to water collected from the likely points of user collection (LPUC; e.g., spring box, spring pool, pipes) and results show that a higher percentage of LPUC samples were considered Unsafe, while a higher percentage of groundwater upwelling samples were considered Low Risk/Safe: 35% for upwelling and 40% for LPUCs. Water at springs was commonly contaminated with Intermediate to Unsafe levels of E. coli: >70% and >65% of springs sampled at the upwelling and spring box, respectively. E. coli was present even at springs “protected�? by spring boxes, indicating that this infrastructure does not prevent contamination of spring water. Recommended future work includes using relatively low-cost, portable rock-coring machines to drill wells at mountain springs for studying the extent of bacterial and nitrate contamination by accessing safe groundwater tens of meters below ground for community water supply.