Predetermined Height Research Articles

Risk of Chondral Fracture During Implantation of Distal Femur Osteochondral Autograft Plugs: A Human Cadaveric Comparison of Four Different Donor Regions.

Distal femoral cartilage lesions can be treated using osteochondral autograft transfer (OAT). When impacting plugs into a recipient site, the cartilage may fracture. This study aimed to analyze OAT donor regions and impaction energies to identify characteristics that lead to fracture. Fifteen cadaver femurs were used with OAT plugs harvested from the following regions: lateral and medial trochlea (LT and MT), lateral and medial intercondylar notch (LIN and MIN). Plugs were impacted into a bone surrogate block using a custom anvil-type system with pre-determined impact heights; 30, 50, 70, and 90 mm. Each plug's cartilage was examined and determined to be intact or fractured. Chi-square was used to compare the rate of chondral fracture for each region. In all, 221 plugs were included. The overall rate of chondral fracture was 45.7%. There was a significant difference in the rate of fracture between regions, with LIN, MIN, LT, and MT, having a fracture rate of 46.6%, 62.7%, 25.0%, and 51.9%, respectively (P = 0.001). An impact height of 30 mm resulted in a fracture rate of 17.7%. Increasing the impact height from 30 to 50 mm resulted in significantly increased chondral fracture risk (P = 0.001). Different donor regions have varying rates of chondral fracture during OAT plug impaction, with the lateral and medial trochlea being the most resistant to chondral fracture at lower forces. Increased impact energy increases risk of chondral fracture. Surgeons should maintain caution and utilize lower impact energy when inserting OAT plugs.

Development of an Automatic Scissors Screw Car Jack

In this paper, an existing manual scissors screw car jack was converted to an automatic scissors screw car jack by introducing a sleeve coupling between the manual screw jack and a 12V DC electric motor, which is powered through a direct current energy flow directly from the car battery. The DC electric motor provides a turning effect to automatically power the screw jack for the purpose of lifting the desired load. A screw jack (manual or automatic) is a simple machine used in lifting heavy loads. It becomes very useful in vehicles when changing a punctured tire. It is mandatory for each vehicle plying an approved road to carry a jack for fixing a punctured tire. However, the operation of most car jacks is done manually and also requires prolonged bending or squatting positions when using the jack, making it difficult for most women, the disabled, the elderly, etc., and above all, not ergonomically suitable for the human body due to crouching and squatting positions when in use, which may result in health complications. The automatic scissors car jack developed was successfully tested on five different types of vehicles, with different weights. Five different tests measurements were carried out on each vehicle. The time taken to lift the vehicles 0.03 m off the ground was recorded. They ranged from 74 s to 90 s depending on the weight of the vehicle involved. The heavier the vehicle, the longer the time taken to lift the vehicle off the ground to the predetermined height of 0.03 m.

Poster 281: What Donor Region has the Lowest Risk of Fracture During Insertion of an Osteochondral Autograft Transfer Plug: A Human Cadaver Analysis

Objectives: Treatment of some cartilage tears in the knee can be reliably treated with an osteochondral autograft transfer (OAT) procedure. A cylinder plug of donor cartilage and bone is extracted from one region of the knee and impacted into place of a recipient region where there is a void of hyaline cartilage. During this procedure, care must be taken when impacting the donor plugs into place. The cartilage on the donor plug is prone to cracking or fracturing if it is impacted with excessive force. The objective of this study was to analyze different donor OAT regions to determine if any area is more resistant to fracture or cracking than other donor sites. Methods: Four donor site regions of the knee were tested where the OAT plugs could be harvested for transplant. The four donor regions were the lateral trochlea (LT), medial trochlea (MT), lateral intercondylar notch (LIN), and medial intercondylar notch (MIN). Using eight cadaver distal femurs, a total of 75 cartilaginous plugs were taken from each donor. This resulted in a total of 300 donor OAT plugs from all four donor sites. To harvest the plugs, a 6mm OAT harvest kit (Arthrex, Naples, FL) was used to obtain each donor plug. Each harvested plug was then impacted into a 6 mm hole that was previously created in a sawbones bone surrogate block. The hole in the bone block was created to mimic a cartilaginous defect found in the knee. The tested plugs were impacted with a standardized anvil type system with pre-determined heights that were recoded as heights 1-4. These increasing heights were set to simulate increasing forces applied during impaction. Each plug was only used one time and for only one height. After impaction of each sample, the cartilage of the plug was analyzed. The cartilage was considered intact or cracked based on visual inspection. A chi-square analysis was used to compare the rates of cartilage damage for each donor region and impaction height. Results: Seventy-five plugs were tested for each donor region. The specific donor regions had a fracture rate of 40%, 62.5%, 28% and 52.5% for the LIN, MIN, LT, and MT, respectively. There was a significant difference in fracture rate between each donor site (p<0.001). The LT region had the overall lowest rate of fracture at all heights during impaction. The lowest impaction height had an overall fracture rate of 16%, while the highest impaction height had a fracture rate of 50%. With increasing impaction force there was an increase in OAT chondral fracture (p<.001). At the lowest impaction force, the percentage of fractured cartilage was 17.4%, 35.7%, 4.0%, and 6.7% for the LIN, MIN, LT, and MT, with a difference between them (p=.04). Conclusions: This study found that the LT donor site provided the overall lowest rate of fracture and withstood the highest forces of impaction of the four donor sites. At lower impaction forces, both the MT and LT had low chondral fracture rates. The OAT procedure is a great option for cartilage tears of the knee. Damage to donor plugs is very possible with high forces during impaction and must be taken into consideration during surgery. The study shows that the LT seems to be more resilient to damage and should be considered when choosing donor sites for patients that may require high impaction forces.

The calibration device research for assessing the impact exposure level of rubber balls in architectural acoustics

In order to accurately measure the impact exposure level of rubber balls used in architectural acoustics, a calibration device is designed based on a force sensor, signal analyzer, programmable stepper motor and Infinite Impulse Response (IIR) filter. A weighing sensor with a range of 200 kg is selected to match the range of impact forces of rubber balls. The sensor is installed on a specially designed metal base plate of a rubber ball measuring fixture and connected to the signal analyzer. The rubber ball is dropped from a predetermined height in a free-fall manner to impact the sensor, generating an impact waveform. The force exposure level is then calculated by using software algorithms built into the device. The accuracy and reliability of the calibration device are evaluated by conducting repeated measurements on rubber balls and comparing the results with a known standard force exposure level curve. The experimental results demonstrate that the calibration device can consistently and stably measure the force exposure level of rubber balls, showing consistency with the known standard values. However, due to limitations such as a limited variety of measured objects and insufficient measurement repetitions, further research will be conducted to increase the number of tested rubber balls and enhance the device’s capabilities. This will provide technical support for the further development and application of the device.

Experimental periprosthetic fractures with collarless polished tapered cemented stems.

After cemented total hip arthroplasty, the risk of periprosthetic fracture (PPF) of taper-slip stems is higher than that of composite-beam stems. We aimed to assess the conditions resulting in PPFs of taper-slip stems using a falling weight. Taper-slip stems were fixed to five types of simulated bone models using bone cement, and the fractures were evaluated by dropping stainless-steel weights from a predetermined height onto the heads. The periprosthetic fracture height in 50% of the bone models (PPFH50) was calculated using the staircase method. For the fixation with 0° of flexion, the values for PPFH50 were 61 ± 11, 60 ± 13, above 110, 108 ± 49, and 78 ± 12cm for the cobalt-chromium-molybdenum alloy, stainless steel alloy (SUS), titanium alloy (Ti), smooth surface, and thick cement mantle models, respectively; for the fixation with 10° of flexion (considering flexure), the PPFH50 values were 77 ± 5, 85 ± 9, 90 ± 2, 89 ± 5, and 81 ± 11cm, respectively. The fracture rates of the polished-surface stems were 78.6 and 35.7% at the proximal and distal sites, respectively (p < 0.05); the fracture rates of the smooth-surface stems were 14.2 and 100%, respectively (p < 0.05). The impact tests demonstrated that the conditions that were less likely to cause PPFs were use of Ti, a smooth surface, a thick cement mantle, and probably, use of SUS.

Development of Autonomous Hexacopter UAVs for Smart City Air Quality Management

Monitoring the pollution index in smart cities has piqued the interest of researchers in designing and developing unmanned aerial vehicles (UAV) capable of carrying several sensors. Recent advancements in drone technology, as well as rapid expansion in air pollution sensor technologies, have presented valuable alternatives for air quality monitoring and management in smart cities. Fixed stations are now used in smart cities to measure air pollution and collect precise data on air quality. However, such data is highly sufficient in making decisions that can improve people lives; monitoring stations require an adaptable and large communication network that is capable to handle such huge data. Instead of having such an expensive and complex network, drones could be considered an easy and cheap alternative to the current systems. In this regard, an aerial system that is equipped with off-the-shelf low-cost micro-sensors is designed and implemented to monitor air quality at a specific location inside a smart city. The behavior of the aerial system is controlled by our proposed Air Quality-Driven Control Algorithm (AQDCA). Hexacopter Drone, in particular, will fly up to a predetermined height, measure air pollutants, activate the on-board AQDCA, and then return to its ground location. The entire system was developed, implemented, and tested in a real-world flight test. The testing results corroborate the system’s practicality and demonstrate that the prototype may be simply implemented to provide an added-value service to smart city citizens.

Design and Development of a Double-chamber Down Draft (DcDD) Pyrolyzer for Biochar Production from Rice Husk

This study describes the design and development of a pyrolysis reactor for continuous biochar production using rice husk. The main purpose was to invent a simple technology with minimal specific operational requirements which could be operated easily under field conditions. The designed novel double-chamber downdraft (DcDD) reactor comprised of an insulated outer cylinder for energy generation, inner cylinder for pyrolysis, and a condensing system. During the study, temperature behavior, energy interactions, and biochar properties were employed to evaluate the performance of the reactor. The operational temperature was monitored continuously at four predetermined heights and a temperature profile was observed at a range of 380 to 685 °C on the cylindrical reactor. Design configuration and thermal conservation techniques helped to achieve a heat loss as low as 0.81 MJ/kg biochar. The results revealed that the thermal efficiency of the DcDD reactor was 57% with an average biochar production rate of 10 ± 1 kghr-1. It consumed 35 ± 3 kghr-1 of rice husk as the feedstock and 14 ± 5 kghr-1 of rice husk as fuel. With the achieved operational capacity and thermal efficiency, DcDD reactor is a suitable option for converting the discarded biomass to a demanding product which will enhance the soil properties in agricultural production systems.

"Effect of Palatal Metal Collar's Height on Fracture Resistance of Single Metal-Ceramic Crowns".

Objectives The purpose of this study is to evaluate the effect of the palatal metal collar height on the fracture resistance of metal-ceramic crowns. Materials and Methods A maxillary premolar typodont tooth was prepared and scanned to fabricate 48 metal analogs. The analogs were then scanned to fabricate metal copings divided into 4 groups according to palatal metal collar height as follows; (C0): 0 mm, (C1): 1.0 mm, (C2): 1.5 mm, and (C3): 2.0 mm. After a standard application of pressed ceramic, each crown was cemented onto its corresponding metal tooth analog. The crown-analog assembly was subjected to a sequence of thermal stressing for 5,000 cycles. A universal testing machine applied controlled loads to the crowns until fracture. Examination under a stereomicroscope determined the failure mode. A scanning electron microscope (SEM) was used to examine fracture. Load to failure data was analyzed using ANOVA followed by Tukey HSD (P ≤ 0.05). Results ANOVA statistics revealed that groups with a palatal metal collar presented significantly higher failure loads when compared to the collarless group (P < 0.0001). Difference in failure loads between 1.5-mm and 2.0-mm palatal metal collar height were not statistically significant (P = 0.935). There were no significant differences detected among the groups in terms of failure mode. Conclusions The height of the palatal metal collar has an effect on the fracture resistance of the metal-ceramic crowns. Clinical Relevance. The incorporation of a palatal collar with a predetermined height is essential to reduce the mechanical failure of metal-ceramic crowns.

Numerical study on mass transfer in a falling film on structured plates with micro-baffles

• Falling film microreactors were structured with horizontal and inclined baffles. • Inclined baffles caused a pair of swirling flow vortices in a thin liquid film. • Mass transfer coefficient ( k L ) increased by 45% by decreasing baffle interval. • k L increased by 61 % by increasing baffle height. Falling film microreactors are applied to fast gas-liquid reactions to utilize a high interface area per liquid volume. The reaction rate in such reactors is still mass transfer-limited because the flow is laminar, and mass transfer occurs only by diffusion. Therefore, it is desirable to induce convective mixing in thin liquid films. In this study, multiple baffles with a predetermined height of 0.1–0.2 mm were constructed at equal intervals of 1–3 mm on a flat plate to induce a swirling flow, that is, convective mixing, in the liquid. Two types of microstructured plates with horizontal and alternately inclined baffles (IBs) with predetermined angles of 30–60° were designed, and CO 2 absorption into water was numerically investigated for the mass transfer coefficient on the liquid side ( k L ) at Reynolds numbers ranging from 28 to 111. The IB plates outperformed the standard plate without baffles because of the IB-induced swirling flow in a ∼0.2-mm-thick liquid film. k L was increased by 61%, as compared to the standard plate, by adopting a baffle height of 0.2 mm, angle of 45°, and interval of 2 mm, achieving process intensification.

Responses in growth and emissions of biogenic volatile organic compounds in Scots pine, Norway spruce and silver birch seedlings to different warming treatments in a controlled field experiment

We investigated the responses in growth and emissions of biogenic volatile organic compounds (BVOCs) in Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies [L.] Karst.) and silver birch (Betula pendula Roth) seedlings to a simulated climate warming of +2 °C (T2) and +4 °C (T4), compared to the ambient conditions, during two growing seasons (2019–2020) in a controlled field experiment in central Finland. In all seedlings, height was measured weekly. Diameter was measured continuously for one seedling from each tree species per plot. For shoot and root biomass measurements, half of the seedlings were harvested at end of the first growing season and the rest at the end of the second growing season. Foliage BVOC emission rates were measured at the end of the second growing season. Biomass, height, and diameter growth of silver birch did benefit the most from warming in both growing seasons. In the Scots pine and Norway spruce seedlings, height and diameter growth increased with increasing temperature in the second growing season, more so in Scots pine. Overall, the shoot and root biomass of conifer seedlings increased with increasing temperature. In the conifer seedlings, warming increased biomass and diameter growth more than height growth, due to their predetermined height growth pattern. The warming increased BVOC emissions more clearly in silver birch, whilst the BVOC emissions were in conifers less sensitive to temperature variation. Based on our findings, silver birch seedlings could be expected to benefit the most from warmer growing conditions and Norway spruce the least.

Design, Analysis and Development of Digging and Roller Chain Conveying System for Self-Propelled Onion Harvester

Abstract: The history of Agriculture in India dates back to Indus Valley Civilisation. India ranks second worldwide in farm outputs. As of 2018, agriculture employed more than 50% of the Indian workforce and contributed 17–18% to the country's GDP. India has the largest net cropped area, followed by the US and China, yet mechanization in farming is comparatively low compared to developed countries. The lack of technological development and unaffordability of new and competent machines for the average farmer are the few of the reasons for this encumbrance. The development of the onion harvester intends that it will provide a reliable and affordable alternative to traditional farming practices. The digging and conveying systems are the integrated part of the onion harvester. The design of the blade and conveyor is made by using CATIA V5 and analysis of the parts are done using ANSYS Workbench. During design and analysis, severe factors are considered such as preventing the damage to onion bulbs, size of bulbs, soil condition, onion leaves at a predetermined height and roots of the crops to penetrate. This paper is intended to discuss the results of the design and analysis of the digging and conveying systems under the guidelines of the SAE TIFAN rulebook [1]. Keywords: Onion Harvester, Blade Design, Conveyor Design, FEA Analysis.

Mountaineering Risk, Safety and Security

The purpose of this paper is to explore some of the underlying mountaineering risks, safety and security issues found in the traditional activity known as mountaineering. The paper also highlights some of the commonly known and distinguished terms of mountaineering.&#x0D; Mountaineering is the art of moving through the mountains using a set of technical ‘mountaineering’ skills. In Europe, it is often called alpinism when done in the Alps, apart from known as trekking, hiking or even fell walking. It includes traditional outdoor rock climbing in a mountain setting, multi-day rock climbing, skiing, snow-shoeing, a multi-day journey in the mountains, whether camping or in lodges. Mountaineering is not necessarily restricted to the greater mountain ranges as many countries with low altitude mountains have many citizens that go ‘mountaineering’ inside their borders.&#x0D; There are no predetermined heights at which a hill becomes a mountain; many geographers state that a mountain is greater than 300m (1,000 feet) above sea level, but the Oxford English Dictionary puts the hill limit at 600m asl. Another consideration is the latitude of the ‘hills’. For example, the hills of Scotland, although the highest being Ben Nevis at 1345m asl, are considerably further north than the Pyrenees with its highest mountain, Pic Aneto, at 3404m asl. The arctic winds, the northern European winds and the south-westerly gales are as harsh as any found in the higher ranges.

Failure Criteria and Wind-Induced Vibration Analysis for an Offshore Platform Jacking System

Currently, the construction process of large offshore platforms worldwide involves building the topside and hull separately and then having them integrated. Jacking technology is emerging as a new integration method more suitable for offshore platform construction for its higher tonnage and larger scales compared with the lifting technology. Conventionally, an overlapped support tower (OST) is adopted to jack the topside to a predetermined height. However, with the OST’s increasing jacking height, the wind load effect becomes more significant, which in turn limits the OST height and applications. In this paper, failure criteria were developed for the OST based on the load types and structural characteristics of easy assembly and disassembly. Then a simplified method to simulate the OST was proposed. In addition, a finite element model (FEM) of the entire jacking system with the topside and OST (including 6 jacking towers, 8 strand cables and 23 bracing pipes) was established, and wind-induced vibration analysis was performed to ensure safety of the jacking system. The results show that the addition of the topside increases the torsional effect of the jacking system; the unfavorable wind angles are 0° and 15°, which should be paid much attention during the jacking operation. The recommended wind-induced vibration coefficients for the OST and topside are 3.0 and 4.0, respectively. The proposed method and simulation results of this study provide a reference for the jacking and integration design of similar offshore platforms.

Planning model of a group UAV flight in three-dimensional space

The paper describes the algorithm and model for planning group actions of unmanned aerial vehicles (UAVs) to monitor a given set of objects. A distinctive feature of the task is the shooting of objects from a predetermined height. This makes it necessary to move from considering a “flat” model to planning a flight in three-dimensional space. In addition, the authors take into account the possibility of destroying individual UAVs and the need to reschedule the flight route for the remaining UAVs in order to accomplish the assigned task.

AGGREGATED COMPLEXES FOR RICE GRAIN PROCESSING

The paper considers various designs of aggregated complexes for the processing of rice grain. Their technological schemes were built and analyzed, and a breakdown into modules was performed. This allowed us to group the various designs of units and summarize their technological capabilities. The general reduced technological scheme of rice grain processing is considered. The noted variations are as far as practical applications with and without a grain cleaning module. Various schemes of hulling of grain and selection of hulled grain from unlulled are presented. The technological schemes with various hulling machines are analyzed (the Engleberg hulling machine, with rubberized rolls, centrifugal action), which have their own characteristics. The differences in the use of paddy machines and trimers for sorting grain after hulling are considered. The cylindrical trieurs used to select the rice kernel have an original technological scheme (company Yanmar). This allows you to simplify technological communications and make the unit more compact. The units use more compact paddy machines (reduced size, number of tiers, etc.), which, of course, affects their performance. The most common combined machine with a single-pass technological scheme (which was named after the first inventor and manufacturer, a hulling machine from Satake) is considered. In addition to laboratory equipment, centrifugal hulling machines are used in grain processing units, which gives additional advantages (a more compact scheme, due to the combination of several technological operations, hulling, transporting the grain stream, and air separation. For the majority of broken and unbroken grains sieve separators are used for simple circuits. Separators with vertical rotation axis, that allows to transport the rice to a predetermined height. This makes it possible to link this separator, for example with electronic scales.

Grayscale Nanopixel Printing at Sub-10-nanometer Vertical Resolution via Light-Controlled Nanocapillarity.

Nanotextures play increasingly important roles in nanotechnology. Recent studies revealed that their functionalities can be further enhanced by spatially modulating the height of their nanoscale pixels. Realizing the concept, however, is very challenging as it requires "grayscale" printing of the nanopixels in which their height is controlled within a few nanometers as a micrometric function of position. This work demonstrates such a high vertical and lateral resolution grayscale printing of polymeric nanopixels. We realize the height modulation by exploiting the discovery that the capillary rise of certain photopolymers can be optically controlled to stop at a predetermined height with sub-10-nm accuracy. Microscale spatial patterning of the control light directly extends the height modulation into a two-dimensionally patterned, grayscale nanopixel printing. Its utility is verified through readily reconfigurable, maskless printing of grayscale nanopixel arrays in dielectric and metallo-dielectric forms. This work also reveals the highly nonlinear and unstable nature of the polymeric nanocapillary effect, expanding its understanding and application scope.

Autonomous monitoring, analysis, and countering of air pollution using environmental drones

The effect of air pollution on the environment, economic and health of the people in the affected countries cannot be overemphasized. This paper investigates large scale air pollution elimination to remove pollutants that are already in existence in the environment. This method involves the use of Environmental Drones (E-drones) to autonomously monitor the air quality at a specific location. The E-drone flies up to a predetermined height (Ealtitude) every hour, measures the air pollutants at that location, implements on-board pollution abatement solutions for pollutants above the recommended threshold, and then flies back down to its location on the ground. The advantages of this system is its ability to measure air pollution concentration of CO2, CO, NH3, SO2, PM, O3 and NO2, detect when they are too high, and implement on-board pollution abatement solutions as needed. This system's novelty lies in the fact that it not only detects when there is excessive pollution, but it also automatically deals with and abates the detected air pollution above earth. When multiple E-drones are used in different locations, a custom software generates an Air Quality Health Index (AQHI) map of the region that can be used for present and long-term environmental analysis.

Compaction Effort for Uniform Laboratory-Prepared Cohesionless Soil Bed

Abstract Laboratory testing in geotechnical engineering plays a paramount role in developing theories and empirical formulas. Soil preparation is an integral part of any experiment, which is often required to prepare uniform cohesionless soils in the testing tank. One of the oldest methods to obtain the desired unit weight throughout the testing tank is by dropping the sand from a predetermined height. This method often suffers from particle segregation, which reflects on the test results. Applying compaction effort on the surface of the soil is another method for soil preparation that is widely used because of its simplicity and the repeatability of its results. The procedure is followed by trial and error by adjusting the thickness of the layer and the appropriate energy level until the desired relative density is achieved. However, this technique often produces overconsolidated sand in the testing tank, which is usually ignored. Using compaction effort, uniform sand in the testing tank is achieved by placing the sand in layers; each receives a predetermined compaction effort. In this procedure, the majority of the energy applied is used to compact the immediate top layer, while the rest seeps through to the lower layers, increasing their compaction level. Accordingly, by adjusting the level of the energy applied to each layer, it is possible to produce uniform homogeneous sand in the testing tank. This article presents a laboratory procedure to produce a uniform sand bed and to measure the level of the overconsolidation in the testing tanks, namely, by controlling the thickness of the sublayer and the level of energy applied on each layer.

Impact of Vibration on Double-Porosity Unsaturated Laterite Soil with Different Water Contents

Engineering practices, natural and man-made vibrations phenomena such as blasting, construction machinery and operations, and vehicle traffic vibrations can cause stresses to soils. In addition, changes in moisture content may affect the speed of liquid penetrating the soils. Therefore, the impacts due to vibrations and changes in moisture contents need to be addressed to ensure geo-environment sustainability. This can be achieved by conducting laboratory experiments to determine the behaviour of deformable double-porosity soil samples with different water contents subjected to non-repeated vibrations. In this study, aggregated laterite soil samples were prepared with 30% and 34% moisture contents. Each aggregated soil was poured into an acrylic column then the soil was compressed to a pre-determined height of 10 cm. Testing was performed on each soil column using a vibrating table where accelerometers were installed to measure high-frequency acceleration time histories on the surfaces of the vibrating table and laterite soil. The tests were conducted by increasing the amplitude of displacement and the acceleration time histories were collected to record maximum amplitudes. The results showed that the soil surface acceleration in non-repeated vibration was increased with increasing moisture contents. It was also discovered that the speed of liquid penetration was influenced by vibration due to rearrangement of soil particles and changes in soil structure and porosity characteristics.

Square Layout Four-Point Method for Two-Dimensional Profile Measurement and Self-Calibration Method of Zero-Adjustment Error

An on-machine measurement method, called the square-layout four-point (SLFP) method with angle compensation, for evaluating two-dimensional (2-D) profiles of flat machined surfaces is proposed. In this method, four displacement sensors are arranged in a square and mounted to the scanning table of a 2-D stage. For measuring the 2-D profile of a target plane, height data corresponding to all measuring points are acquired by means of the raster scanning motion. At the same time, pitching data of the first primary scan line and rolling data of the first subsidiary scan line are monitored by means of two auto-collimators to compensate for major profile errors that arise out of the posture error. Use of the SLFP method facilitates connection of the results of straightness-measurements results obtained for each scanning line by using two additional sensors and rolling data of the first subsidiary scan line. Specifically, the height of a measuring point is calculated by means of a recurrence equation using three predetermined height data for adjacent points in conjunction with data acquired by the four displacement sensors. Results of the numerical simulation performed in this study demonstrate higher efficiency of the SLFP method with angle compensation. During actual measurement, however, it is difficult to perfectly align inline the origin height of each displacement sensor. With regard to the SLFP method, zero-adjustment error is defined as the relative height of a sensor’s origin with respect to the plane comprising origins of the other three sensors. This error accumulates in proportion to number of times the recurrence equation is applied. Simulation results containing the zero-adjustment error demonstrate that accumulation of the said error results in unignorable distortion of measurement results. Therefore, a new self-calibration method for the zero-adjustment error has been proposed. During 2-D profile measurement, two different calculation paths – the raster scan path and orthogonal path – can be used to determine the height of a measurement point. Although heights determined through use of the two paths must ideally be equal, they are observed to be different because accumulated zero-adjustment errors for the two paths are different. In view of this result, the zero-adjustment error can be calculated backwards and calibrated. Validity of the calibration method has been confirmed via simulations and experiments.