Clearance Distance Research Articles

Feasibility study of an earth-retaining structure using in-situ soil with dual sheet piles

Classic braced walls use struts and wales to minimize ground movements induced by deep excavation. However, the installation of struts and wales is a time-consuming process and confines the work space. To secure a work space around the retaining structure, an anchoring system works in conjunction with a braced wall. However, anchoring cannot perform well when the shear strength of soil is low. In such a case, innovative retaining systems are required in excavation. This study proposes an innovative earth-retaining wall that uses in situ soil confined in dual sheet piles as a structural component. A numerical study was conducted to evaluate the stability of the proposed structure in cohesionless dry soil and establish a design chart. The displacement and factor of safety of the structural member were monitored and evaluated. According to the results, an increase in the clearance distance increases the depth of safe excavation. For a conservative design to secure the stability of the earth-retaining structure in cohesionless dry soil, the clearance distance should exceed 2 m, and the embedded depth should exceed 40% of the wall height. The results suggest that the proposed method can be used for 14 m of excavation without any internal support structure. The design chart can be used for the preliminary design of an earth-retaining structure using in situ soil with dual steel sheet piles in cohesionless dry soil.

Developing an algorithm to assess the rear-end collision risk under fog conditions using real-time data

This study aims to propose a new algorithm to evaluate the rear-end collision risk under fog conditions considering reduced visibility. The proposed algorithm compares the safe stopping distance of the leading and following vehicles. According to the relationship between clearance distance between the two consecutive vehicles and visibility distance, the car-following maneuver is divided into different situations and the algorithms to calculate the safe stopping distances are suggested correspondingly. The visibility distance is collected by a new visibility detection system with adaptive learning modules and the clearance distance is obtained from a vehicle-based detector. By comparing the safe stopping distances of the following and leading vehicles, the potential rear-end collision can be identified. Subsequently, statistical tests are conducted to analyze rear-end collision risk and compare the different impact of reduced visibility on the collision risk for different vehicle types and lanes. Furthermore, random parameters logistic and negative binomial models are estimated by using individual vehicle data and aggregated traffic flow data, respectively, in order to explore the relationship between the potential rear-end crash and the reduced visibility together with other traffic parameters. The results suggest that the proposed algorithm works well in evaluating rear-end collision risk under fog conditions. It is found that reduced visibility has significant impact on the rear-end collision risk and the impact vary by the different vehicle types and by lane. Further, it is concluded that the driving maneuver of the leading and following vehicles can affect the rear-end collision risk. It is expected that the proposed algorithm can be implemented in a Traffic Management context to improve road safety under fog conditions. Specifically, it is suggested to implement the proposed algorithms in real-time and integrate it with ITS technologies such as Variable Speed Limit (VSL) and Dynamic Message Signs (DMS) to enhance traffic safety when the visibility declines. This car following algorithm could also be extended to adapt for the advent of Connected Vehicles in Fog conditions.

Fading characteristics of maritime propagation channel for beyond geometrical horizon communications in C-band

The design of a maritime communication system requires the understanding of the wireless propagation channel above the sea. For broadband communication systems, a carrier frequency in the C-band is of interest because of allocatable spectrum. Therefore, the German Aerospace Center performed a long-distance channel measurement campaign at 5.2 GHz on the North sea to investigate large and small-scale fading characteristics. The results show that our measurement data conforms with the ITU-R and the Bullington’s path loss model to predict the power loss caused by diffraction over the Earth’s surface. Further, the first tap of the channel impulse response experiences Rician fading due to superposition of a strong line-of-sight (LoS) path and multipath components originating from the sea surface and ship body. We found that the fading of the second tap follows a Rician distribution, but with a much smaller K-factor compared to the first tap. The K-factor showed a dependence on the distance between the transmitter and receiver. Particularly, the K-factor of the first tap decreases significantly when the distance between the transmitter and receiver is larger than the clearance distance of the first Fresnel zone. Therefore, we propose a distance-dependent K-factor model for the first and the second tap.

Pre-aligned downwind rotor for a 13.2 MW wind turbine

Abstract While there is continued demand for larger wind turbines with cheaper cost of energy, conventional upwind blade design may be reaching a size limit stemming from blade failure at extreme wind conditions. For turbines rated above 10 MW, decreasing the structural loads to more manageable levels may be achieved by better aligning the forces along the rotor blade to reduce ultimate bending moments and fatigue loadings. To achieve such moment reduction, a downwind configuration with a coning angle prescribed to allow load alignment for critical conditions could be used. Such a configuration also increases the rated clearance distance between the rotor and the tower since wind loads push the blades further from the tower. This concept is explored herein for a 13.2 MW rated downwind design compared to a conventional upwind three-bladed rotor design that uses the Sandia SNL100-02 blades. The simulation results show in Class IIB winds that the two-bladed downwind pre-aligned rotor with 15° coning, decreases the blade damage equivalent loads by 19.0%, and decreases rotor blade mass by 27.4%, compared with the unmodified conventional upwind three-bladed rotor. However, further design optimization is needed to ensure annual energy production is preserved with this concept.

Safe placement of breakaway luminaire poles behind Midwest Guardrail System

ABSTRACTLuminaire poles are commonly installed along highways to provide proper illumination in critical areas. When placing light poles in close proximity to guardrail, the poles may affect the guardrail's ability to safely contain and redirect vehicles. The interaction between a deflected guardrail system and a closely-positioned light pole may create unwanted stiffening or hinging of the barrier system around the pole. The pole may also present a snag hazard to impacting vehicles and induce vehicle instabilities. In this study, the barrier clearance distance, i.e. the lateral offset away from a breakaway light pole was investigated and evaluated. The minimum safe lateral offset away from the pole with respect to the Midwest Guardrail System (MGS) was determined to be 508 mm (20 in.) through crash testing and computer simulation with non-linear finite-element analysis. Two full-scale crash tests were conducted according to the American Association of State Highway Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) Test Level 3 (TL-3) impact safety criteria. In test no. ILT-1, a 2268-kg (5000-lb) pickup truck impacted the combination MGS with light pole system laterally offset 508 mm (20 in.) from back of posts at a speed of 100.7 km/h (62.6 mph) and an angle of 25.0°. In test no. ILT-1, the pickup truck was captured and safely redirected while impacting the light pole and disengaging the pole away from the base. In test no. ILT-2, a 1098-kg (2420-lb) small car impacted the combination MGS with light pole system laterally offset 508 mm (20 in.) from back of posts at a speed of 100.9 km/h (62.7 mph) and an angle of 25.6°. In test no. ILT-2, the car was safely contained and redirected while minimally contacting the light pole. The MGS with a lateral pole offset of 508 mm (20 in.) away from back of posts to front face of pole provided an acceptable safety performance to MASH TL-3 when critically impacted by a pickup truck and a small car. Thus, a minimum offset of 508 mm (20 in.) between the back of the MGS post and front face of the breakaway pole was sufficient to assure a safe performance of the MGS during vehicle impacts without undesired interaction with the pole. Accordingly, guidance for the safe pole placement behind the MGS was provided.

Study of the Bed Velocity Induced by Twin Propellers

Twin propellers without a rudder were studied using a physical model with a fixed clearance distance and three different rotating velocities. Experimental results were compared with results from theoretical expressions developed over the past 50 years for the efflux velocity, axial velocity, and maximum bed velocity. It was found that the efflux velocity equations overestimated the experimental results, whereas the computed axial velocities matched the experimental data reasonably well. However, when maximum bed velocity expressions were compared with experimental results, only one method was found to behave better; overestimation resulted if a quadratic superposition of single jets was used.

Interaction driver–bicyclist on rural roads: Effects of cross-sections and road geometric elements

The interaction of motorists and bicyclists, particularly during passing maneuvers, is cited as one of the primary causes of bicyclist fatalities. This paper reports the results of a driving simulator study, which sought to analyze the effects that three cross-section configurations of a two-lane rural road and four geometric elements of the road have on driver behavior, during the interaction with a cyclist. A two-lane rural road, about 11km long, was designed and implemented in an advanced-interactive driving simulator. Three different cross-sections (all with same width, but with and without a bicycle lane and for different widths of bicycle lane) were tested. Forty participants carried out three driving sessions (one for each road alignment with different cross-section) and were exposed to the condition of bicycle traffic along four geometric elements of the alignment (2 tangents with different lengths, right curve and left curve). The driving simulator experiments were designed in such a way that, along the sections where the driver–cyclist interactions occurred, the oncoming traffic was absent. Overall, 468 speed profiles and 468 lateral position profiles were plotted to obtain the descriptive variables of the driver behavior during the interaction with the cyclist. The influences of cross-sections, geometric elements and bicycle traffic conditions on driver behavior were evaluated by a multivariate variance analysis. The presence of the cyclist determined different levels of influence on driver’s trajectory for the three cross-sections. A wider bicycle lane ensured a higher later clearance distance between driver and cyclist, allowing safer overtaking maneuver.The interferences of the cyclist on driver’s behavior depended on the geometric elements. On tangents, the lowest lateral clearances were recorded and no speed reduction was observed, compared to the cyclist absence condition. On the left curve, the higher lateral clearance was recorded, due to the concordant tendencies of the driver to move away from the cyclist and to cut the curve. This determined an excessive and risky displacement of the vehicle to the opposing lane, whose criticality was also emphasized by the high speed adopted by the driver. On the right curve, the lateral clearance was higher than that recorded on the tangents, probably due to the necessity of the driver to perform the demanding maneuver of entering in the right curve, which also determined a speed reduction compared to the cyclist absence condition.The obtained results provide suggestions for the most efficient cross-section reorganization of existing two-lane rural roads in order to improve the road safety.

Modeling and simulation of 2.5 MVA SF6-gas--insulated transformer

In recent years, environmental awareness has been a great concern, and even governments have sometimes been under pressure to comply with bilateral agreements. Mineral oil/epoxy cast resins are one of the most harmful soil pollutants. Of course, they provide a good insulation material in (distribution/power) transformers, but they present some disadvantages, such as low ignition point, additional insulation costs, requirement for an extinguishing apparatus, long clearance distance, toxicity, costly decontamination, and explosion risk. For this reason, gas-insulated transformers have nowadays been put into specifications. % This paper investigates SF6-gas-insulated transformer (GIT) designs for the complex distribution transformer model, i.e. 2.5 MVA open-air type. The model has 34.5/0.4 kV, 50 Hz ratings. SF6 GITs present more reliable working conditions due to the inherited specs of SF6 because it has nonflammable insulation and an explosion-proof design. Therefore, the proposed transformer design is mostly suitable for security risk environments, such as submarines, mines, and nuclear power plants. Apart from these advantages, the new SF6 GIT design is compact in design and lighter than the oil-type or the epoxy cast resin type.

Mechanical Property of 9 Years Old Thinning of Teak Plantation in Thailand

Based on the study of the conditions and problems of thinned teak in Thailand it’s with findings that thinned teak or so called thinning for distance clearance being with small stems and can be sold at low price. thinned teak was with mechanical property different with teak from natural forest with age over 30 years old with the results of most of the tests were with findings that the values of the mechanical property of teak from natural forest with age over 30 years were more valuable than the values of the mechanical properties of thinned teak with exception on Standard Test Method for Tensile and Cleavage Test of Timber which thinned teak was with more value than teak from natural forest with age over 30 years old. For guidelines on market value added for thinned teak can be made by producing to use in the context of the design of household goods made of wood as the guide for resolution of problems and creation of artistic work pieces household goods made of wood.

Differences in drivers’ pedestrian avoidance response based on Warning timing, stimulus-response compatibility and Drivers’ distraction of auditory pedestrian collision warning system

In this study, the effects of auditory pedestrian collision warning system’s stimulus-response compatibility (compatible vs. incompatible) and warning timing(TTC: 2sec. vs. 4sec.) and type of driver distraction (control condition vs. auditory distraction vs. visual distraction) on pedestrian avoidance response were examined. The dependent measures were time to initial steering wheel maneuvering, steering wheel rotation angle, clearance distance to the pedestrian, ratio of pedestrian-collision and ratio of lane departure. The experiment used driving simulator and the results was as follows. First, the effects of stimulus-response compatibility appeared to differ as warning timing and types of driver distraction were varied. To be specific, stimulus-response incompatible condition was more suitable for auditory pedestrian collision warning system than stimulus-response compatible condition. Second, compare to 4sec, 2sec TTC condition yielded larger steering wheel rotation angle and higher ratios both in pedestrian-collision and lane departure. Third, among the types of driver distraction, the visual distraction impaired drivers’ ability to avoid the pedestrian most seriously. In conclusion, stimulus-response incompatible warnings which provided 4sec TTC condition seemed to be more reliable and useful in providing pedestrian-collision warning to drivers.

Effects of above-crossing tunnelling on the existing shield tunnels

Tunnelling in the dense urban areas frequently results in over-crossing or bypassing the existing tunnels. It is obvious that the over-crossing tunnelling will adversely affect and even damage the existing tunnels if the induced deformation exceeds the capacity of tunnel structures. Increasing concerns have been raised about the interactions between the over-crossing tunnelling and underlying tunnels. In order to obtain a better mechanical understanding of the effects of the over-crossing tunnelling on the existing tunnels and provide a quick but low cost assessment alternative method for evaluating the behavior of underlying tunnels prior to construction, a simplified analytical method is proposed in this study. In this simplified method, the tunnel is simply considered as a continuous Euler-Bernoulli beam with a certain equivalent bending stiffness. The unloading stress at the tunnel location caused by the over-crossing tunnelling is computed through Mindlin’s solution, ignoring the presence of the existing tunnel. Then, the tunnel-soil interaction due to the relief stress is analyzed based on the commonly-accepted Winkler foundation model. The applicability of the presented method is validated by three well-documented case histories. Results of these case studies show a reasonable agreement between the predictions and observations. Finally, a parametric analysis is also preformed to investigate the influences of the different factors on the behavior of the existing tunnels, including clearance distance, advancing distance and multiple tunnels construction.

Behavior of piled rafts overlying a tunnel in sandy soil

The present research presents experimental and finite element studies to investigate the behavior of piled raft-tunnel system in a sandy soil. In the experimental work, a small scale model was tested in a sand box with load applied vertically to the raft through a hydraulic jack. Five configurations of piles were tested in the laboratory. The effects of pile length (L), number of piles in the group and the clearance distance between pile tip and top of tunnel surface (H) on the load carrying capacity of the piled raft-tunnel system are investigated. The load sharing percent between piles and rafts are included in the load-settlement presentation. The experimental work on piled raft-tunnel system yielded that all piles in the group carry the same fraction of load. The load carrying capacity of the piled rafttunnel model was increased with increasing (L) for variable (H) distances and decreased with increasing (H) for constant pile lengths. The total load carrying capacity of the piled raft-tunnel model decreases with decreasing number of piles in the group. The total load carrying capacity of the piles relative to the total applied load (piles share) increases with increasing (L) and the number of piles in the group. The increase in (L/H) ratio for variable (H) distance and number of piles leads to an increase in piles share. ANSYS finite element program is used to model and analyze the piled raft-tunnel system. A three dimensional analysis with elastoplastic soil model is carried out. The obtained results revealed that the finite element method and the experimental modeling are rationally agreed.

Assessment of electromagnetic field levels from surrounding high-tension overhead power lines for proposed land use.

The surrounding outdoor environment for new development has a big effect on the indoor quality of life. The main aim of this work was to determine the suitability of the area for building new schools with reference to electromagnetic field (EMF) effects. The specific objective of this study was to detect the safe distance from the EMF posed by the high-tension overhead power lines in the vicinity of the specified area. The measurements were taken for both the electric and magnetic fields in different months in order to detect the highest EMF levels during the peak power load season. EMDEX II with E-probe and EMDEX II with Linda were used for the measurements. These instruments were all calibrated by ENERTECH Company in USA. The EMF associated with high tension transmission lines that surrounded the proposed site has to be below 0.2 μT (Italian EMF regulations are the most suitable regulations for the establishment of schools in Kuwait). The safety clearance distance from the existing 300-kV high-tension power line has been assigned as 200 m and from other existing 132-kV high-tension power line was 50 m. The proposed site with its predefined boundaries has a magnetic field below the Italian EMF regulations for the establishment of new schools.

Cryothérapie pour les tumeurs rénales : le début d’expérience de notre centre

To evaluate oncologic and functional outcomes after percutaneous cryoablation (PCA) for renal masses based on our single center experience. We retrospectively identified 26 patients who underwent PCA for 28 tumors between November 2006 and June 2011. Patient's demographics and baseline clinical characteristics, tumor features, perioperative information, and postoperative outcomes we rerecorded. A biopsy was performed systematically before each procedure. Control imaging was obtained at 1, 3, 6 and 12 months, and yearly thereafter. Oncological outcomes were determined by radiographic evidence of tumor recurrence, which was defined by contrast enhancement at the cryoablation site on control imaging at M3. Patients had mean age of 70.1 years, mean Charlson comorbidity index (CCI) and body mass index) were 6 and 29 kg/m(2) respectively. There were 11 kidney transplants, including 4 solitary. Mean tumor size was 29.5mm and was represented mainly by clear cell renal cell carcinomas (16/28), endophytic (17/28) and midkidney (14/28) (±9.8). Twenty-five cryoablations were performed percutaneously by two lumbotomy. Mean clearance preoperative MDRD was 66,1 mL/min. Mean length of stay was 3.3 days (±2.2). Intraoperative complications consisted of 2 pneumothorax and 6 minor complications postoperative (Clavien≤2). There were no major complications. Mean follow-up was 27.5 months (±15.7), MDRD clearance distance was 61.9 mL/min. Overall survival and disease-specific survival was 100%, while the recurrence-free survival was 78.6% (5 recurrences and 1 failure treatment). The percutaneous cryoablation provides a safe and oncologically to extirpative surgery for renal masses in patients with significant medical comorbidities. 5.

Fluid flow and heat transfer characteristics of a vertical channel with detached pin-fin arrays arranged in staggered manner on two opposite endwalls

This work investigates the fluid flow and the heat transfer characteristics of a vertical parallel plate channel filled with protruding partial length, high density meshing fins on the two inside walls, considering electronic equipment cooling as one of the possible applications. The goal is to understand the flow physics and quantify the overall heat transfer enhancement achieved. Air is used as a coolant and is assumed to have constant thermo-physical properties. Full three dimensional Reynolds-averaged Navier–Stokes equations and the energy equation are solved using finite volume method for the conjugate heat transfer problem in hand. The standard k-є turbulence model with enhanced wall treatment is used to model turbulence closure, in a Reynolds number range of 2200–23,000. The performance of the system is evaluated in terms of the thermal resistance, separately defined for two plates and the pumping power. The numerical results are validated against experimental results, obtained by performing steady state forced convection heat transfer experiments in a vertical wind tunnel facility. A detailed parametric study considering the clearance distance between the plates, pin-fin diameter, transverse pin fin pitch and axial pin fin pitch as the design variables has been undertaken. From the numerical results, it is seen that the pin-fin diameter is the most dominating variable for both the pressure drop and the thermal resistance. The results of the parametric study are used to train an Artificial Neural Network using the Levenberg–Marquardt algorithm to obtain surrogate models for the objective functions. A multi-objective optimization, based on geometrical parameters, is performed using multi-objective evolutionary algorithm, NSGA-II to minimize the thermal resistance and the pumping power simultaneously. A global Pareto optimal set consisting of non-dominated solutions is then obtained using NSGA-II and is divided into five clusters by k-means clustering method to arrive at representative solutions for each cluster.

双自由曲面大视场头盔显示光学系统设计

Field-of-view(FOV) is the key performance indicator to evaluate a head-mounted display (HMD) in areas such as virtual reality. In order to overcome the difficulties of a sharp increase of optical system aberrations with the increased FOV, a wide FOV HMD optical system with double freeform surfaces was proposed. First, the principles of the double ellipsoid HMD which could achieve large FOV and low distortion were analyzed, and the reason of the aberration correction limitations of the double ellipsoid HMD was pointed out. Then wide FOV HMD optical system with double freeform mirrors was proposed. Two free-form mirrors were used by the new optical system which were symmetrical in vertical direction and asymmetrical in horizontal direction to correct off-axis aberrations brought by increasing FOV. The FOV of the new optical system was 106.3(H)80(V). The maximum relative distortion is 6.97%. The exit pupil diameter was 8 mm and the eye clearance distance was 19 mm. Through tilt outside 8 the binocular FOV was 122.3(H)80(V) and the binocular overlapped FOV was 90.3(H)80(V). The IPD is adjustable within 55-71 mm. The analysis of optical performance indicates that image quality is greatly improved, and the relative distortion and FOV can meet the application requirements of the virtual reality.

LTE MIMO Antennas on Variable-Sized Tablet Computers With Comprehensive Band Coverage

A two-antenna system with comprehensive coverage on 690–960-MHz and 1710–2690-MHz Long Term Evolution (LTE) bands is proposed for uses on tablets of different sizes. Two different antenna configurations are employed to reduce coupling. The main antenna is based on an inverted-F structure. Lumped element loadings are used to enhance bandwidth performance. The auxiliary antenna adopts the capacitive coupling element technique to minimize the antenna footprint and reduce its clearance distance to the ground. Implementation issues such as fabrication difficulty, design transportability across platforms, and antenna diversity gain are looked into. Measured results show moderate efficiency and good isolation characteristics with acceptable return loss in LTE bands. Its superior diversity performance is validated with measured effective diversity gain, which confirms that the proposed design is suitable for LTE multiple-input–multiple-output (MIMO) uses.

Pressure variation and effective sensing zone around small leaks inside water pipelines for reliable leak detection

Detecting and locating small leaks in the water distribution networks save water and help in making critical decisions about the network and the infrastructure. In this work, inside-pipe pressure measurements are used to evaluate the local variation of the pressure around small circular leaks as compared to main pipeline pressure, for reliable leak detection. The technique is working for pressurized pipelines and may be used for liquids and gases. In addition, since large leaks are easy to find, the attention is given to detecting small leaks, which are difficult to be detected using the commercial acoustic methods; specifically with plastic pipes. The current study thereafter helps in characterizing the effective zone of pressure sensing around the leak. A pressure probe, mounted on a movable platform, moves inside a water-pressurized pipe very close to the wall in order to measure the pressure variation at the vicinity of the leak. The effects of pipeline pressure, leak size, and the clearance distance between the pipe wall and the pressure probe on the measured pressure drop around the leak are investigated. Results showed that direct pressure measurements inside the pipe can be effectively used for leak detection. The local pressure drop due to the small leak is very localized around the leak and captured within the leak diameter in the longitudinal direction and almost leak-like radius above the leak in the radial direction. As the line pressure increases, the measured pressure drop increases but the zone of pressure variation is still confined around the leak itself. If the sensor is moving over the leak, then the magnitude of the measured pressure drop is inversely proportional to the sensor speed inside the pipe.

Teaching material based on biomechanical evidence: ‘high-jump hurdles’ for improving fundamental motor skills

Summary Study aim: the purpose of this study has been to develop teaching materials to help improve junior high school students’ fundamental ability to repeatedly run and jump with a high and far-reaching travelling motion and to confirm the effectiveness of a new unit using teaching materials that are experimental in comparison to a conventional unit. Materials and methods: one unit emphasized the conventional approach. This unit aims to improve the ability to step over hurdles. To help improve this ability, a ‘step-up hurdle’ was used as the conventional teaching material. This task focused on reducing the up-and-down motion using three hurdles whose height was set lower than those used in a competitive hurdle run. The other unit aims to improve the ability to jump high and far over hurdles. To help improve this ability, ‘high-jump hurdles’ were developed and used as the teaching material. The motor skill task was to clear three hurdles without knocking a hurdle down, with the hurdle height set as high as possible. Such conventional and new units were used for a group of 25 girls and a group of 18 girls in a junior high school (CON and EXP, respectively) and were conducted during six lessons. Results: EXP’s high-jump hurdle scores significantly increased throughout the advanced lessons. While CON did not significantly improve its hurdle running times in a post-test, there was a significant improvement in EXP. Although CON did not significantly lengthen the horizontal clearance distance from take-off to landing in the post-test, there was a significant lengthening in EXP. Conclusions: these findings suggest that new teaching material for teaching hurdling in physical education which aims to improve the ability to jump high and far over hurdles improves hurdle running time and improves the fundamental ability to repeat running and jumping travelling motor skills in contrast to traditional materials.

Impact of margin status and lymphadenectomy on clinical outcomes in resected pancreatic adenocarcinoma: implications for adjuvant radiotherapy.

Adjuvant chemoradiotherapy (CRT) in the treatment of pancreatic ductal adenocarcinoma (PDA) is controversial. Minimal data exists regarding the clinical significance of margin clearance distance and lymph node (LN) parameters, such as extent of dissection and LN ratio. We assessed the impact of these variables on clinical outcomes to more clearly define the subset of patients who may benefit from adjuvant radiotherapy (RT). We identified 106 patients with resected stage 1-3 PDA from 2007-2013. Resection margins were categorized as positive (tumor at ink), ≤1, or >1 mm. LN evaluation included total number examined (NE), number of positive nodes (NP), ratio of NP to NE (NR), extent of dissection, and positive periportal LNs. The impact of these variables was assessed on disease-free survival (DFS) and overall survival (OS) using multivariate cox proportional hazards modeling. In patients receiving adjuvant chemotherapy (CT) alone, greater margin clearance led to improved DFS (P=0.0412, HR =0.51). Range of NE was 4-37, with a mean of 19. NE was not associated with DFS or OS, yet absolute NP of 5 or more was associated with a significantly worse DFS (P=0.005). Whereas periportal lymphadenectomy did not result in improved DFS or OS, patients with positive periportal LN had worse clinical outcomes (DFS, P=0.0052; OS, P=0.023). The use of adjuvant CRT was associated with improved OS (P=0.049; HR=0.29). In patients receiving adjuvant CT alone, there was a clinically significant benefit to clearing the surgical margin beyond tumor at ink. Having ≥5 NP and positive periportal LN led to significantly worse clinical outcomes. The addition of adjuvant RT to CT in resected PDA improved OS. A comprehensive evaluation of resection margin distance and LN parameters may identify more patients at risk for locoregional failure who may benefit from adjuvant CRT.