RADAN® is GSSI’s post-processing software for ground penetrating radar (GPR). Short for Radar Data Analyzer, RADAN was first developed by GSSI in 1984 and released in 1987 to post-process GPR data. This software allows users to select the processing functions that best suits their needs. RADAN is Windows™ based, which provides a familiar and easy-to-use environment for all levels of user experience. In 1994, RADAN changed from a disk operating system (DOS) to Windows.
RADAN 7 Software Options
There are three types of software packages for RADAN 7. RADAN 7 Main is the primary platform for all GPR applications. Users have the ability to customize their RADAN 7 software with additional modules:
3D: The 3D Module allows the user to view and build 3D visualizations. This module helps interpret and annotate complex subsurface structures and is often used to create report graphics.
RoadScan™: The RoadScan Module is used to analyze pavement, base, and sub-base layers in roadways.
BridgeScan™: The BridgeScan Module allows users to process bridge deck GPR data and account for skew angles. Features included aids users to map bridge deck deterioration and export data in multiple file formats, such as .kml and excel.
GSSI also offers two versions of RADAN that are application specific for the concrete inspection and utility locating markets. These packages are separate from RADAN 7 Main and cannot be upgraded.
RADAN 7 for StructureScan™ Mini is designed to process, view and document 2D and 3D data collected with the StructureScan Mini series systems.
RADAN 7 for UtilityScan® is designed to process, view and document 2D and 3D data collected with our UtilityScan product line.
How to Activate RADAN 7
When users purchase RADAN 7, they are provided a unique digital product key and serial number that is needed to install the software on their computer. RADAN 7 will automatically activate purchased modules when the activation codes are input. If one does not input the activation codes, the software will go into Demo Mode for 30 days or 33 uses, whichever comes first. After which, the software defaults to a RADAN Reader version.
When importing your GPR data into RADAN, you will see different files depending on the systems you collected the data on. Below we’ll list out the types of file names and differences between them.
Setting up a Source Directory
Lastly, users should know how to generate and set up a source directory in RADAN before beginning any processing. The source directory tells the RADAN program where to look for the data for processing.
When opening the software, click on the global settings option, which will open a pane on the right side of the screen. Upon double clicking on the word source directory, a file browser will open allowing users to browse the location containing the data for processing. Once this source directory is set to the correct location, clicking “Home > Open” will open that source directory right away.
Note: If “Autosave files” is set to Yes when setting up the source directory, RADAN will automatically save files in the source directory in a folder called “PROC,” short for processed files. Alternatively, “Autosave files” can be set to No, which gives users the ability to rename files as they’re being created.
Geologic and environmental investigations are integral in determining the geology of any work site. Ground Penetrating Radar (GPR) used as Non-Destructive Testing for subsurface exploration remains one of the safest, quickest, and highest resolution survey options available. Researchers and professionals have been using GPR for geophysical investigation for nearly a century and the applications are seemingly endless. From depth to bedrock, ground water exploration, ice and snow investigation, geomorphology, bathymetry, stratigraphy and sedimentation, structural investigation (along with geohazards), and prospecting, we offer a wide range of antenna frequencies with never before seen depth penetration and data quality.
Ground penetrating radar (GPR) offers an accurate, non-destructive solution to mapping the subsurface of the earth. With GSSI GPR antennas, it is simple to locate features of interest and subsurface layers in real time, up to 100 feet or more.
We offer many different analog and digital antennas, giving you the freedom to choose the right combination of depth penetration and resolution. High frequency antennas provide higher resolution, but typically offer limited penetration. Lower frequency antennas collect deeper data, but they do not image small targets or closely-spaced soil boundaries. Whatever your survey requires, we’ve got you covered.
In the restoration industry, the level of understanding of moisture in building materials is generally very high. However, there is a tendency to treat concrete with suspicion and it is not uncommon for waivers to be used to reduce liability for the drying contractor. This is understandable considering there are many unknown variables in concrete, partly due to it being the only building material fabricated on site. Adding to the confusion about moisture in concrete is a mistaken assumption that measuring the vapor in concrete equates to a measurement of the total moisture content in the concrete. This assumption has contributed to many mistakes being made in the flooring and restoration industries. A better understanding of the meaning of measuring both the moisture and the vapor will go a long way to removing much of the confusion and allow for better decision making.
The Importance of Temperature and Equilibrium Equilibrium Relative Humidity (ERH) measurement, as per the ASTM F2170 standard, is a way of measuring the vapor in an airspace in equilibrium with the moisture in concrete as a percentage of the maximum vapor which the airspace can hold. For the results to be meaningful, it is important that the air is in equilibrium with the moisture in the concrete, which is why it is referred to as ERH not RH. However, this does not mean ERH measurement is a measurement of the moisture content. Relative Humidity is used rather than Absolute Humidity because the temperature of the air has a dramatic effect on the amount of vapor the air is capable of holding, making the absolute humidity measurements such as Grains Per Pound meaningless for this purpose.
To explain this simply, the Equilibrium Relative Humidity and the Humidity Saturation Point will both be affected in the same way by the changing temperature. As such, the ERH remains meaningful at different temperatures whereas the absolute humidity levels change. This highlights the need for the humidity to be in equilibrium with the moisture in the concrete, again explaining why it is referred to as ERH and why the temperature must remain stable during the measurement phase. Variables when ERH testing ERH measurement per ASTM F2170 gives useful information about the condition of the concrete but due to variables including the unknown amount of un-hydrated cement present and the unknown level of air permeability of the concrete, it cannot be considered an accurate measurement of the moisture content. To understand this more clearly, the vapor saturation level needs to be considered. It is often assumed that vapor will always saturate at 100% RH but this isn’t necessarily the case.
Take a salt calibration check for example: there is humidity saturation identified by the presence of liquid water but the RH is at 75% due to the presence of salts. Combining Non-Destructive Impedance and ERH Testing Adds Value Measuring the impedance of the concrete is also commonly used to identify the moisture content of the concrete. ASTM F2659 was written to standardize the methodology for carrying out this test. This is a practical site test, which is popular due to its ease and speed of use. However, there are variables which make the moisture content readings less meaningful, especially if we don’t know the vapor level within the concrete. For example, different ambient conditions will alter the Equilibrium Moisture Content (EMC) and different aggregates can absorb and adsorb moisture differently, also affecting the EMC. Therefore, a combination of measuring both ERH and Moisture Content is advisable. The combined approach can be compared to looking down a rifle and lining up two iron sights, instead of one. Ideally, an ERH of 85% will line up to a moisture content of 4% and 90% ERH will line up to 4.5% EMC but when they do not line up there is much information which can be gained about the concrete which would otherwise be unknown if relying on one of these test methods alone.
Many things can be learned about the concrete by combining different test methods, including identifying concrete which is highly alkaline which can have a low ERH to MC level, or identifying concrete with a high Vapor to MC level, which indicates a good quality concrete. Concrete needs a minimum RH of 85% in order for hydration to continue to take place, this hydration will continue to reduce the MC while, ideally, the RH remains at 85% or above until all the hydration is complete. Consider the Ambient Environment and Age of the Concrete Further testing of the ambient conditions is important to improve the meaningfulness of these results, as there are conditions from the environment which can also affect the relationship between the MC and ERH. The age of the concrete also needs to be taken into consideration as most moisture or RH specifications are made for new concrete where construction water is still present. Older concrete, where the moisture should be in equilibrium with the average ambient conditions, is also easier to understand with a combination of testing. Achieving Faster, More Efficient and Reliable Testing With meaningful and simple training, a technician is able to make much more informed decisions based on the data from combined tests, thus removing many of the unknowns as to the condition of the concrete.
Although more testing is carried out, the combined testing should actually be more efficient and much faster. Quick tests such as impedance are used to create a moisture map and more difficult testing such as ERH testing should be used as much as necessary to confirm the vapor condition of the slab, rather than as a method of moisture mapping. This is over time-consuming and doesn’t add to the value of the data. There is little doubt that there is a lot of room for improvement when it comes to testing concrete for moisture that can lead to potential flooring issues. The current methodology has many an expert scratching their head trying to understand the rationale for it. The view of this author is that the combination of ERH and Impedance measurement along with ambient measurements is enough to answer most questions about the condition of the concrete. However it is not the only way that this can be done. There are different methods developed in different parts of the world including tests which combine both humidity and moisture testing and there are several ways to achieve more meaningful information. The first step in improving one’s knowledge is to move away from the idea that one test competes with another, - a doctor would not for example refuse to use an X-Ray because an MRI is better. He or she would use the most practical means available to achieve the information needed to treat a patient, and that’s just pragmatic and good practice.
By Andrew Rynhart
In this article, we will review an interesting category of ultrasonic test methods for concrete inspection and testing: Ultrasonic Pulse-Echo (UPE) is widely used for the inspection of concrete elements. The method has proven to be extremely useful in determining the thickness of concrete elements with one side access (i.e. tunnel linings, trunk sewer linings, abutment walls), detect sub-surface defects such as voids, honeycombing, and delamination, and to verify Location of grouting defects in tendon ducts.
Ultrasonic Pulse Echo
Ultrasonic Pulse Echo is a non-destructive testing (NDT) method for scanning sub-surface targets in concrete elements. UPE methods use acoustic stress waves to study the properties of sub-surface layers, and locate defects by identifying any anomaly of acoustical impedance that is different from concrete. The test method was developed to address practical limitations of the general Ultrasonic Pulse Velocity test, such as the need to access both sides of the concrete element.
The ACI 228.2R Section 3.2.2 provides a comprehensive review on the evolution of ultrasonic pulse echo method, and instruments over the past few decades. While traditional UPE instruments were capable of providing A-Scans and B-Scans, modern Ultrasonic Pulse Echo Tomography devices are capable of providing real-time B-Scans that would enable engineers to see sub-surface targets with further clarity. Mobile-based Applications, along with Artificial Intelligence and Modern signal processing techniques have brought superior speed and clarity, with ease of use.
How Does Ultrasonic Pulse Echo Work?
As we discussed earlier, UPE uses stress waves. The principle concept behind the test is measuring the transit time of ultrasonic wave in concrete. A modern UPE instrument consists of an array of piezoelectric transducers that are capable of exciting concrete surface through short-burst high amplitude pulse-high voltage and high current- (see Strategic Highway Research Program-SHPR2, TRB, 2013). As the pulse propagates within the concrete, it gets reflected and refracted at the interface of voids, or other internal targets. Any anomaly in acoustical impedance leads The emitted impulse and the reflected stress waves are monitored at the receiving transducer. The signals are analyzed to calculate the wave travel time.
According to the SHRP2, “Based on the transit time or velocity, this technique can also be used to indirectly detect the presence of internal flaws, such as cracking, voids, delamination or horizontal cracking, or other damages.”
Applications of UPE Methods
Ultrasonic Pulse Echo methods are widely used in concrete inspection and testing. The following section describes the main applications and Use Cases:
1. Estimate Thickness of Concrete Elements
Ultrasonic Pulse Echo is widely used by engineers to assess the thickness of concrete elements. This is specially important in concrete elements with one-side access (Single Side Access), such as Tunnel linings: Thickness measurement is critical in the QC process for tunnel linings. It is also an important parameter for structural evaluation purpose.
Trunk Sewers: In trunk sewers, UPE can help engineers estimate the thickness of existing lining. This becomes extremely challenging because intrusive methods involving hot work with core drilling is not a safe nor cost-effective solution. Moreover, there is always the risk of coring in shallow sections with high hydro static pressure.
Concrete Tanks: Testing concrete tanks that are used in industrial chemical processes is often challenging. Maintenance managers of such facilities often have very short downtime windows, and permission to get inside the tank is not always practical (unless during essential maintenance cycles). UPE enables thickness measurement and quality assessment from exterior face.
2. Grouting Defects in Tendon Ducts
Along with Ground Penetrating Radar (GPR) and Impact-Echo, UPE can provide critical information about voids and defects that might have happened during grouting process of tendon ducts in post-tensioned concrete elements.
3. Locate Sub-Surface Defects
UPE tomography can be used to assess certain defects in concrete elements. UPE can pinpoint the following defects:
Delamination: UPE methods can be used to assess the location and extent of delamination in concrete bridge decks, parking garage slabs, and concrete tanks. Honeycombing: UPE is a great tool in the Quality Control and Quality Assurance of new construction. UPE can be used to localize honeycombs in concrete. Detailed Bridge Condition Survey - Delamination of concrete in bridge decks. Honeycomb concrete - UPE Scan. Honeycomb area during construction
4. Quality Control and Quality Assurance
UPE can used as in-direct method to assess the overall quality of concrete. Through the measurement of pulse velocity, engineers can evaluate the quality of concrete materials after construction.
5. Evaluation of Fiber Reinforced Concrete
While GPR has certain pratical limitations in evaluation Fiber Reinforced Concrete (FRC) elements, UPE methods provide a reliable alternative in thickness measurement and quality control of elements. This makes them an interesting alternative in inspection and testing of concrete linings in tunnels.
Limitations of UPE and Practical Considerations
Like all other NDT methods, UPE comes with its practical challenges for certain field conditions.
Close Spacing of Test Points: In order to generate reliable and precise maps of sub-surface defects, engineers need to use close spacing between test points. This can make the test time-consuming for large test areas. A practical solution is to use another method such as GPR for rapid screening, and use UPE for high-resolution imaging of defects.
Coupling Issues: The quality of acoustic signals depend heavily on the coupling of the transducer and concrete surface. This cab be quite challenging for rough surfaces. Modern devices have tried to address the issue with spring supported mechanism at the base of transducers to allow for maneuvering around the rough areas.
Undetected Defects: Certain defects might remain undetected. This is specially true for very shallow flaws or when operators work with low frequencies.
Welcome to another blog about Ground Penetrating Radar. This post is from GSSI Academy and provides GPR theory basics and key concepts of ground penetrating radar. In this post, we discuss how to determine different material types when conducting underground utility locating surveys.
GPR Theory: Determining Material Types
One of the most critical tasks in using Ground Penetrating Radar, or GPR, technology is that of determining materials types for materials in the ground. Given that GPR technology works by transmitting and receiving a high frequency electromagnetic wave through the ground, distinguishing between different materials – typically air, water, and metal – is possible by analyzing the degree of difference in the dielectric constant of the material. Dielectric constant measures how easily radar waves move through a material; for more in-depth information about it, check out this blog post.
Air, Water, or Metal?
For underground utility locating, the three main material types encountered are metal, air, and water. Determining material type is possible by analyzing dielectric change, or the change in how easily radar waves penetrate the ground as compared with the material in the ground. The larger the dielectric change, the stronger the reflection and the brighter the image produced on the GPR control unit. Greater change produces brighter targets on screen, and smaller changes produce dimmer targets. The color of the target onscreen indicates whether the dielectric change is positive or negative.
Metal has an infinite dielectric constant – GPR cannot pass through metal because it’s a perfect reflector for GPR energy – and so it will be shown onscreen as the brightest possible positive dielectric change.
Whereas an air-filled PVC pipe, through which the radar energy moves easily, will demonstrate a negative change, since the dielectric constant of air is less than that of ground materials. The data image below shows a water-filled PVC pipe that clearly identifies the top and bottom of the pipe.
The same is true when identifying underground voids. Below is an example of a well-defined void underneath a reinforced concrete slab with an asphalt overlay.
Finally, in the case of a water-filled PVC target, the screen will show a positive change like that of metal because water has a higher dielectric constant than any ground materials. Determining water targets compared to metal, however, is possible because while water has a high dielectric constant, it is not impermeable to GPR and thus will show up as a dimmer positive target on the screen of a GPR unit.
In this new blog we present a new chapter from GSSI Academy. It is a basic introduction to some of the key concepts of ground penetrating radar. To begin, we discuss the importance of the dielectric constant and methods to determine the right dielectric. Just as Ground Penetrating Radar is also known as GPR, Georadar, and ground probing radar, the term dielectric constant can also be known as velocity and medium type, depending on specific GPR manufacturers.
GPR Theory: Understanding the Dielectric Constant:
GPR works by transmitting and receiving a high frequency electromagnetic wave through the ground, whether it’s soil, concrete, gravel, or other material. Radar waves travel at different velocities depending on what material it’s traveling through; anything ‘different’ that it interacts with will produce a reflection, to be received by the GPR device. Upon receiving the reflection, a GPR device will take note of the amount of time it takes for the signal to return and the strength of that reflection. The system will take these two pieces of information and convert them into a depth reading; in order to do so, they must be programmed with what’s known as the dielectric constant. This constant describes the speed at which electromagnetic waves move through a particular material.
The Importance of the Dielectric Constant:
The dielectric constant is critically important to getting accurate depth readings with GPR systems. Dielectric constants, also known as relative dielectric permittivity, are measured on a scale of 1 to 81, where 1 is the dielectric constant for air (through which radar waves travel most quickly) and 81 the constant for water (through which radar waves travel most slowly). Metallic objects exist outside the scale, since radar waves cannot penetrate them at all; they are described as having an infinite dielectric constant.
In order to convert the variable that is produced by a radar reading – time – into the desired product of the reading – depth – GPR systems must be accurately programmed with the correct dielectric constant for the ground material in question. This enables GPR systems to produce meaningful depth readings, instead of timed reflection readings; these time reflection readings are transformed in an equation with the proper dielectric constant. As a result, depth readings from GPR systems are only as accurate as the dielectric constant with which they are programmed for each particular ground material. There are three key methods for determining an accurate dielectric constant, each with their own benefits and drawbacks.
Methods of Determining the Dielectric Constant:
One way of determining the dielectric constant is by utilizing a published reference, available from GSSI in manuals and products documentation, as well as online. Using a published reference is the quickest and easiest way to obtain a dielectric constant because it doesn’t require field analysis if ground material type is known. It’s not the most accurate, though, because published references are averages and not site specific.
A more accurate way to determine the constant can be with utilizing a method known as migration, or hyperbola fitting. Hyperbola fitting relies on data gathered from pipe-like targets in the ground; individual GPR units are capable of calculating dielectric constants for different soils simply by fitting a hyperbola tool to hyperbola data gathered in real-time from one of these pipe-like targets. This is the most consistent way to determine the dielectric constant in the field.
The final method for determining the dielectric constant is through what’s known as ground truth. In this case, a GPR unit is positioned over something for which the actual depth is known; by programming the unit with this known depth (known from a prior dig or a chart), the unit can calculate the dielectric constant and effectively gauge depths for other objects in the field.
Load testing is a common practice among bridge engineers for the assessment of bridge safety and serviceability. Diagnostic load testing is one type of load test methods that can be used either as a means for estimating the load carrying capacity of an in-service bridge or as an acceptance test before the bridge is put into service [Olaszek et al, 2014]. This article provides a quick review to Diagnostic Load Testing of Bridges and its application to bridge condition assessment.
Diagnostic Load Testing
Bridge Load Testing-Diagnostic Load Tests can be used to evaluate specific response characteristics of the bridge such as lateral load distribution and secondary stiffening effects and to validate the load rating analytical models.
Diagnostic load testing usually involves installation of a variety of sensors, including:
strain gauges, acceleration sensors, displacement sensors and highly sensitive rotation devices.
Sensors are normally installed on structural components. The test is generally performed with controlled load situations. Applied loads are typically limited to legal load levels or load levels that are known to be safe for a particular structure (historical data).
The main goal of the diagnostic load testing of bridges is to identify structural response (deformations, strains, etc.) for a given load condition. The measured responses are compared with those that are derived from the analysis of the theoretical models, for the same loading condition. Head to head comparison is then used as the basis for validating the theoretical model and defining how accurately the model simulates actual load paths [Santini Bell et al, 2013; Shahsavari et al, 2019].
The field portion of diagnostic load tests can be executed with low-cost because they can be done quickly and with minimal impact on traffic. The load testing vehicle is typically a legally loaded dump-truck and the instrumentation is installed in temporary fashion which can usually be installed in a day with a small crew. Actual tests are conducted with brief road closures or moving blockades to minimize conflicts with the traveling public.
Diagnostic Load Testing for Structural Model Calibration
The ability to calibrate a structural model is the primary concept behind diagnostic load testing. The basis of comparison can be static and/or dynamic structural responses generated by a known loading condition. Static measurements are often global responses such as midspan displacement and girder rotation at an abutment or local member cross-section responses such as axial or flexural deformation obtained from strain measurements. Dynamic measurements usually consist of acceleration, which are further processed to generate structural mode shapes and natural frequencies.
The calibration of the Finite Element (FE) models using the monitoring data helps reduce possible errors induced by simplifications or inaccurate assumptions made in model development. Wrong assumptions are mostly due to insufficient knowledge about structural details, materials properties, inevitable simplifications of the details or ignorance of the non-structural components, and boundary conditions. In the model calibration procedure, prior to refining the wrong assumptions made in the model developments, it is essential to determine the important parameters causing a deviant response in the model. The refinement attempts are required to change the recognized influential parameters and minimize the errors until the desired accuracy is achieved.
Performing load tests with moving loads can be very efficient and minimize impact on traffic, but it requires that truck position be monitored and recorded along with all the structural responses. The key part of diagnostic load testing is an apples-to-apples comparison of data. This requires a convenient method for extracting field data for specific truck positions corresponding to the simulated load cases from the model. The procedure is based on direct comparison of responses for many sensor locations and many different load cases. The load test results are a series of response histories as a function of load position.
Relative Services to Bridge Condition Assessment
When a bridge experiences an unexpected occurrence of accidental events, such as truck accident, a major concern for bridge managers is effective and informed operational decision-making with respect to the remaining capacity of the bridge. Given the load rating reduction estimated by the bridge analytical model, an integrated decision-making protocol combining different approaches will be beneficial to bridge managers for making decisions on the damaged (pre-repair) state of the structure with respect to different damage scenarios. A calibrated structural model helps establish a baseline to determine the structural system response for performance prediction and investigate the bridge decreased load carrying capacity under different damage scenarios [Shahsavari et al, 2020].
Monitoring a bridge’s structural response has the potential to:
detect the presence of structural changes for condition assessment,
inform the bridge manger to assist in daily operational decision-making,
validate the structural design assumptions,
refine a structural model of the bridge to be used for performance prediction [Read More].
Unlike conventional load test practices which have the potential to induce damage into bridge components (e.g., PS/C girders) and reduce its serviceability, diagnostic load testing of bridges appears to be promising for determining the bridge maximum safe load capacity through analytical investigations. The structural models calibrated through controlled load tests would be beneficial for operational decisions such as those relating to maintenance scheduling and overweight vehicle permitting.
Diagnostic load testing would measure structural performance at the applied test loads but not provide any indication as to how the bridge would behave at higher loads or what the effective factor of safety would be for legal post loads. Creating a calibrated structural model that can predict the impact of operational and environmental variations on bridge performance provides support for better management strategies such as fatigue performance prediction, load rating deterioration and real-time condition assessment.
To obtain a realistic capacity, an alternative approach would be a combination of diagnostic and traditional load testing procedures in such a way that loading a bridge up to its serviceability limit without inducing any damage to the structure or cause any reduction to service life. The use of Structural Health Monitoring (SHM) sensors being deployed at critical locations may be warranted to examine bridge performance over time. The measured parameters include, but not limited to, changes in stress in critical regions, changes in deflection, identification of crack activity, etc.
Moisture testing devices are an integral tool for the restoration industry. Though a team of professionals can employ every piece of equipment on a job site, unless the damaged or dampened building materials are free from moisture to a required standard, the job will not be satisfactory for the long term.
Tramex moisture meters make it possible to identify and track the source and extent of moisture problems without destroying the materials being tested. We design our products to fit your needs because we know working conditions on the job site, such as tight spaces, difficult to reach places, corners, curves, and textures, are challenging. These areas can only be correctly measured with the precise moisture meter.
We also know, the sheer variety of materials required to be tested demands using the right restoration moisture meter. How do you know you have the moisture meter for the restoration project? Here are a couple of things to consider:
How quickly you can get a measurement
The type of scale(s) on the meter
The depth moisture can be detected
How do you determine the best moisture meter for your next restoration project? Here's a quick overview.
The Moisture Encounter ME5 provides an instant measurement and evaluation for a wide range of building materials
The Concrete Moisture Encounter CME5 is a non-destructive meter for measuring moisture content instantly in concrete slabs
A digital version of the CME4 handheld the CMEX II provides instant and precise measurements in concrete and other floorings (incorporating the optional Hygro-i plug-in ports transforms it into an exemplary all-in-one instrument)
The MRH III is a handheld digital moisture meter calibrated for most building materials (the optional plug-in Hygro-i2 makes it suitable for water damage restoration, flooring, checking indoor air quality, inspectors and pest companies)
A mobile and non-destructive impedance device, the Dec Scanner is excellent for surveying instant moisture of roofing and waterproofing, checking for water leaks, and integrity tests
For a pocket-sized meter, the Skipper Plus is non-destructive and is a comprehensive, safe method for detecting excess moisture in boat hulls and fittings
The handheld PTM 2.0 digital, pin-type meter takes exact measurements in wood, drywall products, and comparative WME (Wood Moisture Equivalent) values in wood by-products as well as more than 500 wood species
The options of different moisture measurement meters from TRAMEX make it a versatile tool for restoration experts. It is precisely what professionals need to shore up the exactness required in many contracts.
With in-built quality you can trust, you can count on an investment in TRAMEX by having ownership of a quality product to bring you serviceability for years to come.
Because of the versatility of the GEM-2 instrument, our customers are constantly finding new ways to use it. One application is the measurement of sea ice thickness in the polar regions. Both airborne and ground-based EMI (ElectroMagnetic Induction) have been used before to estimate sea ice thickness. Because of its moderate length (<2 metres) the GEM-2 can easily be mounted in a kayak or sled for towing.
There many parallels between ice measurements and a traditional ground conductivity survey. The simplest assumption for data analysis is a layered model, with the seawater conductivity much greater than that of the sea ice, snow and air above it. (> 2,000 mS/m vs. < 100 mS/m). But the picture is more complicated when ice-platelet clusters form under the ice. These are clumps of crystalline ice which float in the seawater on the underside of the ice layer; their density and depth, and hence bulk conductivity, are highly variable. They will cause errors in ice thickness measurements if not taken into account.
Scientists from the Alfred Wegener Institute of the Helmholtz Centre for Polar and Marine Research in Germany have developed calibration and deployment methods for characterizing sea ice shelves in the Antarctic. In particular, they have been able to exploit the GEM-2's advanced capabilities to perform more complex characterizations than simply measuring ice thickness.
Scientists conducted expeditions to various locations with and without platelet formations. They used the GEM-2 to record response at several frequencies, for different heights and correlated these results with physical measurements at that location, the 'ground truth'. They found that having independent measurements for both in-phase and quadrature at each frequency reduced the ambiguity of the recorded signal, leading to more accurate calibrations. Also they found the higher frequencies (63 kHz and 93 kHz) most useful in characterizing the platelet layer. These types of measurements are not available from more primitive single-frequency/fixed frequency instruments.
Many free-air calibrations were carried out to estimate any long-term drift and temperature dependency of the GEM-2; temperatures ranged between -10 C and -24 C . They did not observe a strong temperature dependence of the zero-level offsets for any frequency, and the instrument performed well. The cold affected the capacity of GEM-2 batteries; this was solved by keeping a spare battery inside someone's coat while the other battery was in use. The GEM-2 comes with a spare battery, and a battery change takes less than a minute, so near-continuous surveying is easy.
The GEM-2 itself is made of industrial-grade components rated from -40 C to +85 C, so operating temperatures are not normally an issue.
This post is based partly on the paper "Towards an estimation of sub-sea-ice platelet-layer volume with multi-frequency electromagnetic induction sounding" by Priska A. Hunkeler, Stefan Hendricks, Mario Hoppmann, Stephan Paul And Rüdiger Gerdes. The paper is at https://epic.awi.de/id/eprint/36936/
Other photos courtesy of Alfred Wegener Institute ( www.awi.de )
We partner with RTUTec to bring you an affordable solution for the #COVID pandemic. The solution employs thermal imaging cameras to measure the skin temperature of passengers, company workers, big audiences passing through certain checkpoints. People exhibiting elevated skin temperatures, which may indicate a fever, could then be isolated for further evaluation to determine the cause. Similar quarantine procedures may help minimize the spread of the Corona Virus outbreak. ThermApp MD is a vital tool for fever detection in high-risk areas.
Uniquely calibrated to measure temperature differences on human skin.
Supported devices: Android 8 and up.
Includes Mini Android Single Board Computer source.
Available in a 6.8mm and 19mm lens configuration.
Please contact us for more information and orders.