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Pakistan upset the odds at the 1992 World Cup as they lifted the trophy in Australia with victory over England in the final.
Former captain Imran Khan, now a politican, recalls one of the highlights of his career
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Conditions were not in Pakistan's favour in Australia. How confident were the team before the start of the competition?
I always entered every event with a self-belief that I could win, although our team had a bad track record in Australia. To add to that we had several injuries.
Waqar Younis had to return home - he was bowling at his fastest at that time so it was a huge blow - Saeed Anwar and Ata-ur-Rehman also fell unfit.
So we had new players like Aamir Sohail, Inzamam-ul-Haq and others like Iqbal Sikander and Waseem Haider, who were never heard of before or after the Cup.
You hear it all the time - "metabolism", but what is it? It's the process of converting food to energy (movement and heat). Metabolism happens in your muscles and organs and the result of it is what we commonly refer to as "burning calories". Metabolism is essentially the speed at which your body's motor is running.
"Basal metabolism" is the metabolic rate or caloric expenditure needed to maintain basal body functions such as your heart beating, breathing, muscle tone, etc. It's how fast your "motor" is running when you're still in a reclined position or sleeping. Basal metabolism accounts for about 75% of the calories you expend on a daily basis!
On any surface or body that is submerged in water or any other liquid, there is a force acting because of the hydrostatic pressure. Learn how to determine the magnitude of this force.
Forces on planar surfaces
If the surface is planar, a single resultant point force is found, mechanically equivalent to the distributed pressure load over the whole surface.
This resultant point force acts compressively, normal to the surface, through a point termed the “center of pressure”.
Its magnitude is: F=γzkA, where:
The choice between Petrol cars and Diesel cars is highly debated right from the inception of these two engine types. There have been endless discussions on this topic among car enthusiasts across the world including India. This article is dedicated to comparing these two most famous engine variations.
The domestic refrigerator is one found in almost all the homes for storing food, vegetables, fruits, beverages, and much more. This article describes the important parts of the domestic refrigerator and also their working.
Parts of the Domestic Refrigerator and how they Work
The domestic refrigerator is one found in almost all the homes for storing food, vegetables, fruits, beverages, and much more. This article describes the important parts of the domestic refrigerator and also their working. The parts of domestic refrigerator can be categorized into two categories: internal and external. Let see these in details along with their images.
The finite element analysis (FEA) or finite element method (FEM) or computer aided engineering (CAE) is used widely. What is FEA? How CAE works? The article will discuss these all using a flow chart for a typical finite element analysis.
What is Finite Element Analysis?
The finite element analysis (FEA) or FEM is a problem solving approach for the practical (engineering)
Welding is a well established process of joining metals together, and a great advancement on riveting. However, some welds failed when put under load, prompting a more thorough method of inspection of welded joints Nowadays there are various techniquesfor non-destructive testing of welds (NDT)
Introduction to Nondestructive Testing of Welding.
When I served my time in Harland and Wolff shipyard in Belfast in the 1960’s, welding had thankfully taken over from riveting. My old next door neighbour had been a riveter on the Titanic and was stone deaf due to the constant hammering of the pneumatic equipment used in those days.
What is Computer Aided Design?
The CAD or the computer aided design process is the enrichment of the traditional manual design process by using computer software and hardware extensively. By using computer the whole design process becomes much faster and robust.
The output of a computer aided design process typically is 2D and/or 3D geometry like curves, surfaces and solids. But often the CAD geometry also contains data like material properties, dimensions, tolerance and manufacturing process specific information.
A typical computer aided design process has the following steps:
•Conceptual system design: Initially, a very rough CAD model of the system is being created without considering the strict dimension control. The main purpose here is just to visualize the product idea.
•Freezing the concept: By reviewing the conceptual system the concept is being frozen. And thus the system level assembly is being finalized.
•Detail component design: The detailed CAD geometry of the individual components is then created with appropriate dimensions and tolerances.
•PDM: Product data management is the database for the CAD geometry and the related documents. In simple term, PDM helps systematic access and revisions of CAD data.
•CAE: The detailed CAD geometry is then used as input for computer aided engineering (CAE) or finite element analysis (FEA) to know whether the geometry will sustain the loading condition or not, if not then required modification is done for the CAD geometry and so on.
•CAM: Once the CAD geometry passed FEA, it then used as input for the computer aided manufacturing for generating NC codes. This NC codes are fed to the CNC machines for manufacturing the components.
How Does CAD Work?
•A CAD software package and sometimes a graphics card must be installed there in your computer for a typical CAD system to work.
•The heart of a CAD software package is its graphics kernel.
•Another important part of the CAD packages is the GUI. The GUI is used for getting user input and displaying the CAD geometry.
•Most of the times, the mouse and the key boards are used as input devices however, the little unknown devices like: tracker ball, digitizer etc are also used sometimes.
•As shown in the above picture, the input from the input devices go to GUI, the GUI then send the input to the graphics kernel in suitable form. The graphics kernel generates the geometric entities and signals the graphics card to display it through the GUI. This is the explanation of the working of a CAD system in a simplest form.
Conclusion
The basic difference between the CAD package and the other software package is that the CAD package has to handle large amount of graphics data and thus the graphics kernel explained in “How does CAD Works?” section is very important. The computer aided design process dicussed under the "What is computer aided design?" section are the outline of the process and may vary from situation to situation.
Introduction
Instead of simply one pipe inside another, as for a double pipe heat exchanger, a shell and tube heatexchanger uses multiple tubes in a bundle inside of a 'shell'. This gives a more compact heat exchanger for a given heat transfer area, but the flow patterns are somewhat more complicated for a shell and tube heat exchanger. The diagram at the left shows the general configuration. Some of the shell and tube heat exchanger options that affect the flow pattern are U-tube or straight tube and how many passes (tube side). The shell side flow pattern is determined by baffles as shown in the diagrams.Compressor Safety
A compressor in a refrigeration or air conditioning plant has to be provided with some safeties to protect it from operational faults. The three common safeties provided are the high pressure trip, the low pressure trip, and the low oil pressure trip among the others. A compressor has to be protected against high pressure that can cause structural failure therefore a high pressure cut out is provided, similarly any deficiency in the oil pressure can damage the bearings and a low oil pressure cut out has to be provided, a lower atmospheric in the pipe line can cause air ingress and therefore must be avoided. In this article we discuss the different safeties one by one.
High Pressure Cut Out
High pressure can be caused in a refrigeration plant due to various causes like over charge, loss of cooling water, high ambient temperature, air, or other incompressible gases in the system, and obstruction in the discharge line of the compressor. For protecting the compressor from high pressure and subsequent failure, a high pressure cut out is provided that take a pressure tapping from the discharge line and when it detects an over pressure, it stops the compressor. The HP cut out is not resettable automatically but has to be reset manually by the operator. This is because the high pressure is a serious fault and the cause must be investigated and corrected before the plant is started again.
Construction of High Pressure Cut Out
Operation of a High Pressure Cut Out
The high pressure cut out as shown in the diagram is of a simple construction. It has a bellows that is set against a spring. The nut at the end of the spring is used to adjust the cut out pressure. When the high pressure gas enters the bellow, the bellow expands and presses the spring. At the cut off pressure the movement of the bellow against the spring releases the catch and the contact is broken and the compressor cuts off.
The switch arm can be pressed and the cut out reset after the cause of the over pressure has been found and rectified.
Low Pressure Cut Out
To protect the compressor against low pressure in the system and to avoid the ingress of air into the system if a vacuum is generated in the lines a low pressure cut out is provided. Also when the refrigerated compartments are cut off by the solenoids and there is no return gas, the low pressure cut out is activated. When the solenoid of the refrigerated compartments open, the return gas comes in the inlet of the compressor and the suction pressure rises, and then the low pressure switch cuts in the compressor.
Unlike the high pressure cut out, the low pressure cut out is self-resettable and does not need to be reset manually.
Low Pressure Cut Out Layout
Low Oil Pressure Cut Out
The oil is pumped under pressure by an attached oil pump that supplies oil to the bearings for lubrication. Any problem in the lube oil pressure can jeopardize the bearings and therefore a tapping is taken from the pump outlet and fed to the oil pressure switch. Any fall in the pressure will activate the cut out which will stop the compressor.
Oil Separator
As oil is miscible with the refrigerant and often goes out of the compressor with it, it can go to the evaporator where it can cause a decrease in heat transfer. To avoid the oil from going to the evaporator where it can form a layer inside or cause obstruction an oil separator is used. It basically consists of baffle plates that separate the oil from the refrigerant and feed it back to the compressor. A float valve is provided so that short circuiting of the refrigerant should not take place.
Oil Separator Construction
Conclusion
The refrigeration plant compressor has to be protected against unnatural working conditions by safety devices and controls. The high pressure cut out, the low pressure cut out, and the low oil pressure cut out are some of the basic protective devices provided. In large complex circuits other additional safety devices are provided according to the complexity of the circuit.
The nuclear power plant and the fossil thermal power plant both use steam to convert the heat or thermal energy to mechanical rotation to rotate the generator to produce electricity. Only the heat source is different. In a nuclear plant, the heat source is from the nuclear reaction whereas in a thermal power plant it is from the combustion of coal.
The difference is in the inlet steam parameters to the turbine in a nuclear plant. Thermal power plants use steam at superheated conditions. In nuclear plants, the steam is at saturated conditions and at a lower pressure. This is due to the inherent design limitations in the nuclear reactors.
In fossil power plants the inlet steam parameters are typically temperatures of 540 º C to 580 º C and pressures of 170 bar or even higher. In addition, there is additional heating in the form of re-heating. In a nuclear plant, the ratings are typically saturated steam at 78 bar, which is steam temperature of 298 º C. The nuclear plant uses a 'wet steam turbine'.
Increased Steam Flow.
The reduced inlet steam parameters in the nuclear plant results in lower thermal efficiencies. Nuclear plants operate at lower thermal efficiencies , lower by more than 10 %. The energy of steam per unit mass entering the turbine is also less.
This results in a very high steam flow for the same MW output, almost double that of fossil power plants.
The configurations of the turbines change due to this. The economics of scale requires the nuclear plants to be in the range of 600 MW to 1000 MW resulting in very big Turbines.
Fossil plants turbines normally have one High Pressure one Intermediate Pressure and a double flow Low Pressure (LP) cylinder.
The LP turbine exhausts to very low pressure. The volume of steam leaving the LP turbine is very high. The higher flows require very long last stage blades to keep the exit velocities and exit loss very low. This results in very high stresses in the blades. The sizing of the LP turbine is limited due to the size of the Last Stage Blades. Therefore, each LP turbine has a flow limitation.
One way to overcome this limitation is to increase the number of LP turbines. Large Nuclear plants have apart from an HP /IP stage two or three double flow LP turbines connected in tandem.
Another way is to reduce the speed. Since the stress on the Last Stage Blades is speed dependent reducing the turbine speed by half reduces the stress resulting in bigger sized LP turbines. In such cases the turbine runs at 1500 or 1800 rpm. This requires specially designed four pole generator rotors. This results in a lower number of LP turbines. This is more helpful in 60 Hz countries.
Wet Steam
Nuclear steam turbines are 'wet steam turbines'.
Since the steam is at saturated conditions, after each stage expansion the steam gets wetter. The water particles result in lower efficiency of the turbine. This results in erosion damage to the blades. In addition, this results in vibrations and stress in the last stage. To overcome this nuclear steam turbines use special design of blades and flow paths.
Moisture separators located in the steam path at exit of HP / IP and in the cross under pipes reduce the undesirable effects of the moisture in the steam. Moisture Separator Reheaters also are used. These use extracted steam to aid in moisture removal.
No Reheating
Nuclear steam cycles do not have Reheating as in fossil units. This also reduces the cycle efficiency.
Even with the much lower thermal efficiency, Nuclear power is feasible due to low unit cost of fuel.
Energy efficiency and energy resource management is very relevant in today's context of global warming and climate change. Energy production is responsible for sixty percent of the worlds Green House Gas emissions. The proposed standard is in line with this requirement to help firms and organizations address and reference energy management issues on a global standard.
ISO 50001 is also proposed to be in line with ISO 9001 and ISO 14001 standards that address quality management and environmental management issues. Also, it will have the common elements of ISO's management standards like the continual improvement vide Plan-Do-Check-Act method adopted in the earlier ISO Management standards.
Implementation of ISO 9001 means what the organization does to fulfill the customer's quality requirements,and applicable regulatory requirements, while aiming to enhance customer satisfaction,
Implementation of ISO 14001 means what the organization does to minimize harmful effects on the environment caused by its activities, and to achieve continual improvement of its environmental performance.
Similarly ISO 50001 implementation is expected to address what the organization does to effectively manage energy resources and performance that is relevant to global standards”.
Considering the fact that
•Energy production is the main contributor to GHG emissions.
•Energy efficiency is the quickest and cheapest way to reduce CO2 emissions
•Increased cost of Energy resources
•Reduced availability of fossil fuels and other basic sources of energy in the future.
an international standard was a along felt need. Combining technical and strategic management aspects are expected to give this standard wide acceptability.
The standard is expected to address issue like:
•measuring, reporting, benchmarking energy use improvements.
•assess energy improvement projects impact on GHG emissions.
•create transparency in the management of energy resources.
•evaluate the improvements in implementation of energy efficient technologies.
•validate continuous improvement in energy management.
•promoting a framework for efficient use of energy in the organization.
•helping organizations make a better use of their energy assets.
•helping in procurement practices for energy using equipment and systems.
•emphasis management's commitment to energy use and efficiency.
Boiler Drum.
The most critical part of the boiler in a thermal power plant, Boiler drum functions mainly as the feeding point for the water and separating point between water and steam.
In a typical 600 MW thermal power plant, the drum weighs around 300 Tons. The drum itself is a cylindrical vessel of diameter 1.8 meters,12 meters long, 125 mm thick with dished ends and is made of carbon or alloy steel.
The important point for installation apart from the weight is its location. It is located at a height of around 85 meters, high up in the boiler and hung from the top of the boiler structure.
Installation.
Drum lifting is a milestone in boiler erection that signals the completion of the boiler structure installation.
For the installation of this heavy part following issues require special consideration.
•Installation of a heavy weight at a high position requires special attention to safety in all aspects of the operation.
•The boiler structure is already in place to support the weight which means there is restricted access for using heavy cranes near to the lifting point.
•Interference with the structures already in position, require that during part of the lifting the drum is in an inclined position.
Drum lifting was in the earlier days done using winches and pulley blocks. As the unit sizes and drum weights increased, drum lifting using jacks became the preferred method.
Strand Jack.
Using Strand Jacks has become the convenient method of lifting a boiler drum all over the world. Multiple strands in two or more strand jacks slowly but surely lifts the drum to its position. This is a simple method to lift the heavy weight.
Except for the preparation phase, only one or two operators are required for lifting the drum. Multiple strand jacks offer redundancy, reliability and safety. Using Strand Jacks is easier to install than a winch system and less costly than using a very heavy crane.
The Strand Jack is located on temporary beams on top of the boiler structure above the final position of the drum. Two or four jacks are used based on the lifting arrangement. Lateral movements of the jacks are possible by mounting them on roller skids. This is necessary to maintain verticality and to avoid interference with the supporting structure.
Strands
The jacks itself uses multiple strands, 10 to 14 depending on the load and jack capacity. The lower ends of the strands connect to blocks that fix one end of the strands. The other end of the strands is free and moves through the jack. The blocks connect to the lifting lugs of the drum by links or grommets.
The strands are made of high strength special steels.
Lifting
The lifting operation takes around 8 to 12 hours. The drum lifts off directly from the transportation vehicle. Lifting the drum at an incline is necessary to avoid interference with the supporting structures.The multiple jacks can operate in synchronization or separately. This allows for safe lifting evn if the drum is at an incline. Once it reaches the final position the permenant supports are installed.
The attached figures show the steps in a typical boiler drum installation.
The multiple strands and the positive locking method of the jacks give redundancy, reliability and safety for the entire operation.
Images
.Combine advances in computer models and predictions about group behavior with upgraded video game graphics, and you'll have a virtual world in which defense analysts can explore and predict results of possible military and policy actions, according to computer science researchers at the University of Maryland. The researchers published a commentary on computer predictions in the Nov. 27, 2009, issue of the journal Science.
"Defense analysts can understand the repercussions of their proposed recommendations for policy options or military actions by interacting with a virtual world environment," wrote V. S. Subrahmanian. He's a computer science professor at the university and director of the school's Institute for Advanced Computer Studies.
He and John Dickerson, computer science researcher at the university in College Park, authored the commentary.
Virtual technology can help defense analysts propose policy options and walk skeptical commanders through a virtual world - a world in which one can literally see how things might play out, the pair wrote.
"This process gives the commander a view of the most likely strengths and weaknesses of any particular course of action," they said. "Computer scientists now know pretty much how to do this, and have created a pretty good chunk of the computing theory and software required to build a virtual Afghanistan, Pakistan, or another world.
"Human analysts, with their real world knowledge and experience, will be essential partners in taking us the rest of the way in building these digital worlds and then in using them to predict courses of action," the researchers wrote.
ASME will publish four new standards this month that establish requirements for conducting energy assessments at industrial facilities.
Improving the efficiency of industrial systems increases profitability and reliability, and makes better use of assets. Many industrial facilities have the potential to increase the efficiency of their systems, but have difficulty doing so because there is no market definition for energy efficiency assessment services. Lack of a definition creates problems for service providers in establishing market value for their services and for consumers in determining the relative quality of assessment services.
The standards establish procedures for assessments of a facility's entire systems, from energy inputs to the work performed.
The four standards to be published are:
ASME EA-1-2009 Energy Assessment for Process Heating Systems.
ASME EA-2-2009 Energy Assessment for Pumping Systems.
ASME EA-3-2009 Energy Assessment for Steam Systems.
ASME EA-4-2010 Assessment for Compressed Air Systems.
The energy assessment standards are intended to assist plant personnel in identifying cost-effective projects that often have limited capital requirements. They address the topics and requirements for organizing and conducting assessments, analyzing the data collected, and reporting and documentation.
An assessment may also include recommendations for improving resource utilization, reducing per-unit production cost, and improving environmental performance. These recommended practices will be provided in Guidance Documents which ASME expects to publish by mid-2010.
The new standards are a contribution to the framework for assisting U.S. industry to meet the energy intensity improvement criteria of Superior Energy Performance, the program of the U.S. Council for Energy-Efficient Manufacturing, a partnership of U.S. industry, government, and other organizations.
ASME made four Draft Standards for Trial Use available in late 2008 and asked for comments. The systems assessment community offered extensive comments, and revisions were made to the draft standards and Guidance Documents to better reflect current practices, procedures, and improvements. RYAN CRANE
Mercedes-Benz Debuts New Safety Features in ESF 2009
The German automobile manufacturer Mercedez-Benz has always been known for quality craftsmanship and luxury, but the brand has also been one of the leading developers of safety equipment for automobiles. Mercedes recently took another engineering leap forward by showing off its newest advancements at its American headquarters in Montvale, NJ. These new features, as part of the ESF 2009 concept vehicle, include:
•braking bag
•side doors with gas-fired metal guardrails
•innovative child safety seat design
•interior airbags to protect occupants in rollovers
•shoulder-strap belt airbags for rear passengers
As with all automobile safety features, these components are designed to minimize casualties during automobile impacts by minimizing the forces and accelerations transmitted to the occupants during the impact.
Innovative Braking Airbag
The centerpiece of Mercedes new safety innovations is the braking bag. This specially designed airbag sits beneath the front axle of the vehicle and is designed to deploy 80 to 100 milliseconds before impact. The airbag, coated with heavy-duty rubber and steel, provides several advantages, including increasing the friction between the vehicle and the road, raising the front end of the vehicle to counteract the “nosedive” that occurs during hard braking, and improving the effectiveness of seatbelt tensioners inside the vehicle.
While the increased friction between the braking bag and the road helps to brake the vehicle faster, the lifting action provided by the bag helps to take advantage of the crumple zones in the front end of the vehicle by allowing for better alignment between the vehicle and whatever it is impacting. The lifting action also changes the alignment of the seats and passengers, making interior safety equipment more effective as well.
Additional Innovations in the ESF 2009
The Mercedes ESF 2009 concept vehicle also includes several other interior safety features to protect occupants during a variety of accident scenarios. Interior airbags are designed to keep occupants separated from each other during an impact, particularly in a rollover. Metal side rails help to prevent penetration into the vehicle during side impacts. Shoulder belt airbags for rear seat passengers give occupants of the back seat extra protection. Mercedes has also designed a child safety seat that provides advanced protection for children, particularly in side impacts and rollovers
Roughly at 8:54AM, at 7,500 feet MSL and roughly 2NM from the DCA VOR, I smelled smoke in the cockpit and a moment later I observed the smoke pouring out of the Com 2 (the lower of the two Com radios). It then started to come through around the Com 1, LORAN unit and the Audio Panel. At that point I noticed that the Com 2 display was out.
Fearing the spread of the fire, I started to turn off all un-essential electronic equipment. I first turned off the Com 2 unit the the LORAN unit. I continued to shut down all of the lights on the aircraft and declared "May-Day" to Potomac Approach. According to the DCA airport ops, the May-Day call was made at 8:55AM. After I shut down the lights the smoke ceased. I instructed the front seat passenger, Jim, to prepare the fire extinguisher and be ready to use it. I pressed my hand to the Com radios and the circuit breakers and noticed that they were warmer than usual.
Potomac Approach acknowleged the emergency and asked for my intentions. I requested to land at the closest airport, which was Reagan National (KDCA). I was initially cleared staight in for runway 15 but due to my excess in altitude I informed the controller that I was going to spiral over the field and enter a left downwind to runway 15. While I was over the field I received a hand off to DCA tower and I was cleared to land on runway 19 if I chose fit. I declined and continued my approach to runway 15. Winds at the time were reported as calm. When I entered the downwind leg I observed a small amount of smoke from the radio stack.
After landing we cleared the runway at taxiway M and were met by emergency personnel. At that time I noticed that the Strobe Lights Circuit breaker was shorted. I shut down the engine, evacuated the passengers and assisted the fire and rescue crew in determining that the fire was indeed out and that there was no threat for a relight. After that I taxied the aircraft to the Signature ramp at Reagan Airport.
So thats the official, dry report... now what do I really think?
It happend EXTREAMLY fast. from the moment I smelled smoke until the moment I was on the ground was MAYBE 6 minutes tops.
The first thing that popped in my mind when I saw the smoke was: "OH, look at that! Thats NOT good!"
It was never a doubt that it was an electrical fire. I used to be a volunteer fire fighter when I was younger and I recognized the smell of burning wires and plastics.
When you have an electrical fire, you are supposed to shut down the master switch, but I decided not to. Here's why:
I was flying inside the Washington DC FRZ. This is a VERY delicate area. It requires two way radio communications, transponders and printed waivers and background checks before you can fly in the area. My location at the time was 2 miles west of DCA so in essance, I was also in the airspace of a very busy BRAVO. So to shut down the transponder and lose all radio contact would be unwise and as far as I am concerned, unsafe. So after i shut down the lights and saw that the smoke stopped, I elected to keep one Com radio working and my transponder. All other electrical devices were shut down.
From the moment I noticed the smoke until the moment I declared MAYDAY was maybe 45-60 seconds.
I started a very steep descent from 7500 feet to the deck. There was still a small amount of smoke coming from the radios and I didnt want to wait and see if it would light again. As I descended over the field, I was offered to land on runway 19, but I declined because that would bring me a bit too close for comfort to the washington Monument and P-56, the national Mall (yes I know in an emergency I can deviate from all that, but I was already committed to rwy 15 and I have it instilled in my blood that I DO NOT ENTER P-56).
As I entered the left downwind I saw an ERJ-195 going around from 19 as I crossed its final approach path. I was High and I was fast from my descent and that darn 182 just didnt wanna slow down. On final I was still high and fast. All of a sudden over the radio I heard the voice of the captain from the CRJ that was holding short of 15: "Side Slip her in, you can make it."
He was right and I entered into a side slip and I made the runway. It must have been the ugliest landing in my whole career. Three kangaroos (i was still too fast after the slip). I cleared the runway and all was well. The danger was gone and with the fire fighters and I made sure that the passengers were taken care of and then i helped take off the cowling of the engine just to make sure that the engine was not the cause of the fire. After about 20 minutes on the taxiway, We closed the plane up and taxiied her to the FBO where I was questioned by the TSA, the airport Police, the airport manager and then the FAA.
They were all laughing because I was the first light cessna to land in DCA since Sep. 11th 2001.
And that's it. I hope nobody ever has to face a situation like this, but if you do, just remember to think outside the box - each situation is unique.
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