Getting Started
This topic introduces the Live Health™ applications and
their system requirements.
Live Health Overview
Live Health consists of the following applications:
• Live Exceptions
• Live Status®
• Live Trend
About Live Exceptions
Live Exceptions provides real-time reporting of alarm
conditions to network operations center (NOC) and systems,
application, and network management personnel. It identifies
problems that include delay, errors, failures, security, or
configuration changes. It can display information about alarms
in its Browser, as well as send traps (alarms) to network
management systems (NMSs) and other trap destinations. For
integrated NMSs, users can view a condition, identify the
system component that generated it, and then run eHealth
historical reports to analyze the problem further. Live
Exceptions provides consistency and reduces alarm duplication
by using eHealth historical data to ensure that the alarms are
meaningful. If your account has the appropriate permissions,
you can also acknowledge or annotate an alarm.
Live Exceptions includes default profiles for all technologies.
The profiles organize variables by delay, availability, unusual
workload, and latency. Users with Live Health administrator
permissions define conditions by specifying variables to
examine, thresholds to detect, and intervals over which to
examine the data.
Fault Manager
eHealth Live Health — Fault Manager is an enhancement to
Live Exceptions and the Live Health suite of tools. It allows
eHealth to receive Simple Network Management Protocol
(SNMP) trap messages from other systems and devices and to
take actions based on Live Exceptions alarm rules. Fault
Manager can receive traps from any device or other NMS (such
as HP® OpenView). By default, Fault Manager can recognize a
variety of trap types (that is, it has certified trap types);
however, administrators may define additional trap sources for
use with Fault Manager. You can also request that Concord
certify additional trap types.
Unlike other trap-collecting applications that create logs of trap
messages, Fault Manager interprets and processes trap
information. It reduces the noise of duplicate and repeated
messages and alerts you to the problems and conditions that
interest you. When the eHealth system receives a trap, it
processes the trap based on Live Exceptions rules and profiles
that the Live Health administrator configures. Thus, you can
configure Fault Manager to raise an alarm for the associated
element or to ignore various trap messages.
Fault Manager takes advantage of the eHealth poller
configuration to associate the IP address in the trap message
with an element. You see the more informative element
name—not just the IP address. Thus, when traps raise alarms,
you can drill down to additional reports to obtain more detailed
information about the element and the problem.
If Fault Manager receives a trap for an IP address that eHealth is
not monitoring, it can still report the problem and raise an
alarm for the unknown element.
When Fault Manager receives traps from other sources, it
processes this data as it does data collected by eHealth: it
compares the performance statistics to rules defined in profiles
and generates intelligent alarms when thresholds are exceeded.
You can view these alarms in the Live Exceptions Browser,
which provides access to element-specific drill-down
information when available.
eHealth SystemEDGE and eHealth application insight modules
(AIMs) provide a source for out-of-the-box traps to Fault
Manager. You can use the SystemEDGE agent to monitor
thresholds, processes, log files, Windows® NT events, and
process groups so that you can respond to problems
immediately. A
About Distributed Live Health
Distributed Live Health combines the real-time performance
and availability management offered by Live Health with the
scalability of Distributed eHealth. Distributed eHealth allows
you to monitor up to one million of your critical resources
using several eHealth systems that are connected in a
configuration referred to as a cluster. Distributed Live Health
allows you to monitor and manage the alarms raised by
Live Exceptions across the same one million elements.
From the Live Exceptions Browser running on a Distributed
eHealth Console, you can monitor alarms from systems across
the cluster. You can also drill down on an alarm to view
historical and real-time reports from the eHealth system that
generated that alarm. This allows you to manage the
performance and availability of systems around the world from
a single point.
About Live Status
Live Status provides a high-level view of the current status of
your critical resources as determined by Live Exceptions. Live
Status displays a diagram of the elements in a group list. Icons
that represent the elements are color-coded to reflect their
alarm and monitoring status. You can look at the display and
quickly assess the status of your resources based on color
changes in a logically grouped graph.
You can identify the trouble spots at a glance and quickly drill
down for details to understand the nature of the problem.
About Live Trend
Statistics elements are members
of an eHealth element type that
includes various LAN and WAN
interfaces; Frame Relay circuits;
Asynchronous Transfer Mode
(ATM) paths, ports, and
channels; various components of
routers and systems, as well as the
router and systems themselves;
various remote access resources;
and applications, such as
Microsoft® Exchange and
Oracle™.
Live Trend is an application that you can use to create charts
that monitor statistics elements that you are polling using
eHealth. You can create a single chart or multiple charts in
various styles to represent both element trends (a single
element with multiple variables) and variable trends (a single
variable for multiple elements). Live Trend updates the charts
each time eHealth polls the elements.
You can display the following types of data:
• As polled
• Fast sampled
• Up to 48 hours of history data
System Requirements
A system or workstation that has
an installed version of the Live
Health software is called a Live
Health client.
If you plan to download and install the Live Health applications
on your local workstation, your workstation must meet the
following requirements. Unless stated otherwise, these
requirements apply to all supported language versions of
eHealth.
Sunday, May 24, 2009
TURBOCHARGERS & SUPERCHARGERS by Bhushit Dave(6th sem, EC)
Let's start with the similarities. Both turbochargers and superchargers are called forced induction systems. They compress the air flowing into the engine. The advantage of compressing the air is that it lets the engine stuff more air into a cylinder. More air means that more fuel can be stuffed in, too, so you get more power from each explosion in each cylinder. A turbo/supercharged engine produces more power overall than the same engine without the charging.
The typical boost provided by either a turbocharger or a supercharger is 6 to 8 pounds per square inch (psi). Since normal atmospheric pressure is 14.7 psi at sea level, you can see that you are getting about 50-percent more air into the engine. Therefore, you would expect to get 50-percent more power. It's not perfectly efficient, though, so you might get a 30-percent to 40-percent improvement instead.
The key difference between a turbocharger and a supercharger is its power supply. Something has to supply the power to run the air compressor. In a supercharger, there is a belt that connects directly to the engine. It gets its power the same way that the water pump or alternator does. A turbocharger, on the other hand, gets its power from the exhaust stream. The exhaust runs through a turbine, which in turn spins the compressor.
There are tradeoffs in both systems. In theory, a turbocharger is more efficient because it is using the "wasted" energy in the exhaust stream for its power source. On the other hand, a turbocharger causes some amount of back pressure in the exhaust system and tends to provide less boost until the engine is running at higher RPMs. Superchargers are easier to install but tend to be more expensive
When people talk about race cars or high-performance sports cars, the topic of turbochargers usually comes up. Turbochargers also appear on large diesel engines. A turbo can significantly boost an engine's horsepower without significantly increasing its weight, which is the huge benefit that makes turbos so popular!
In this article, we'll learn how a turbocharger increases the power output of an engine while surviving extreme operating conditions. We'll also learn how wastegates, ceramic turbine blades and ball bearings help turbochargers do their job even better. Turbochargers are a type of forced induction system. They compress the air flowing into the engine. The advantage of compressing the air is that it lets the engine squeeze more air into a cylinder, and more air means that more fuel can be added. Therefore, you get more power from each explosion in each cylinder. A turbocharged engine produces more power overall than the same engine without the charging. This can significantly improve the power-to-weight ratio for the engine.
In order to achieve this boost, the turbocharger uses the exhaust flow from the engine to spin a turbine, which in turn spins an air pump. The turbine in the turbocharger spins at speeds of up to 150,000 rotations per minute (rpm) -- that's about 30 times faster than most car engines can go. And since it is hooked up to the exhaust, the temperatures in the turbine are also very high.
Turbochargers and Engines
One of the surest ways to get more power out of an engine is to increase the amount of air and fuel that it can burn. One way to do this is to add cylinders or make the current cylinders bigger. Sometimes these changes may not be feasible -- a turbo can be a simpler, more compact way to add power, especially for an aftermarket accessory.
Turbochargers allow an engine to burn more fuel and air by packing more into the existing cylinders. The typical boost provided by a turbocharger is 6 to 8 pounds per square inch (psi). Since normal atmospheric pressure is 14.7 psi at sea level, you can see that you are getting about 50 percent more air into the engine. Therefore, you would expect to get 50 percent more power. It's not perfectly efficient, so you might get a 30- to 40-percent improvement instead.
One cause of the inefficiency comes from the fact that the power to spin the turbine is not free. Having a turbine in the exhaust flow increases the restriction in the exhaust. This means that on the exhaust stroke, the engine has to push against a higher back-pressure. This subtracts a little bit of power from the cylinders that are firing at the same time.
Turbocharger Design
The turbocharger is bolted to the exhaust manifold of the engine. The exhaust from the cylinders spins the turbine, which works like a gas turbine engine. The turbine is connected by a shaft to the compressor, which is located between the air filter and the intake manifold. The compressor pressurizes the air going into the pistons.
The exhaust from the cylinders passes through the turbine blades, causing the turbine to spin. The more exhaust that goes through the blades, the faster they spin.
On the other end of the shaft that the turbine is attached to, the compressor pumps air into the cylinders. The compressor is a type of centrifugal pump -- it draws air in at the center of its blades and flings it outward as it spins.
In order to handle speeds of up to 150,000 rpm, the turbine shaft has to be supported very carefully. Most bearings would explode at speeds like this, so most turbochargers use a fluid bearing. This type of bearing supports the shaft on a thin layer of oil that is constantly pumped around the shaft. This serves two purposes: It cools the shaft and some of the other turbocharger parts, and it allows the shaft to spin without much friction.
There are many tradeoffs involved in designing a turbocharger for an engine.
Turbocharger Parts
One of the main problems with turbochargers is that they do not provide an immediate power boost when you step on the gas. It takes a second for the turbine to get up to speed before boost is produced. This results in a feeling of lag when you step on the gas, and then the car lunges ahead when the turbo gets moving.
One way to decrease turbo lag is to reduce the inertia of the rotating parts, mainly by reducing their weight. This allows the turbine and compressor to accelerate quickly, and start providing boost earlier. One sure way to reduce the inertia of the turbine and compressor is to make the turbocharger smaller. A small turbocharger will provide boost more quickly and at lower engine speeds, but may not be able to provide much boost at higher engine speeds when a really large volume of air is going into the engine. It is also in danger of spinning too quickly at higher engine speeds, when lots of exhaust is passing through the turbine.
A large turbocharger can provide lots of boost at high engine speeds, but may have bad turbo lag because of how long it takes to accelerate its heavier turbine and compressor. Luckily, there are some tricks used to overcome these challenges.
Most automotive turbochargers have a wastegate, which allows the use of a smaller turbocharger to reduce lag while preventing it from spinning too quickly at high engine speeds. The wastegate is a valve that allows the exhaust to bypass the turbine blades. The wastegate senses the boost pressure. If the pressure gets too high, it could be an indicator that the turbine is spinning too quickly, so the wastegate bypasses some of the exhaust around the turbine blades, allowing the blades to slow down.
Some turbochargers use ball bearings instead of fluid bearings to support the turbine shaft. But these are not your regular ball bearings -- they are super-precise bearings made of advanced materials to handle the speeds and temperatures of the turbocharger. They allow the turbine shaft to spin with less friction than the fluid bearings used in most turbochargers. They also allow a slightly smaller, lighter shaft to be used. This helps the turbocharger accelerate more quickly, further reducing turbo lag.
Ceramic turbine blades are lighter than the steel blades used in most turbochargers. Again, this allows the turbine to spin up to speed faster, which reduces turbo lag.
The typical boost provided by either a turbocharger or a supercharger is 6 to 8 pounds per square inch (psi). Since normal atmospheric pressure is 14.7 psi at sea level, you can see that you are getting about 50-percent more air into the engine. Therefore, you would expect to get 50-percent more power. It's not perfectly efficient, though, so you might get a 30-percent to 40-percent improvement instead.
The key difference between a turbocharger and a supercharger is its power supply. Something has to supply the power to run the air compressor. In a supercharger, there is a belt that connects directly to the engine. It gets its power the same way that the water pump or alternator does. A turbocharger, on the other hand, gets its power from the exhaust stream. The exhaust runs through a turbine, which in turn spins the compressor.
There are tradeoffs in both systems. In theory, a turbocharger is more efficient because it is using the "wasted" energy in the exhaust stream for its power source. On the other hand, a turbocharger causes some amount of back pressure in the exhaust system and tends to provide less boost until the engine is running at higher RPMs. Superchargers are easier to install but tend to be more expensive
When people talk about race cars or high-performance sports cars, the topic of turbochargers usually comes up. Turbochargers also appear on large diesel engines. A turbo can significantly boost an engine's horsepower without significantly increasing its weight, which is the huge benefit that makes turbos so popular!
In this article, we'll learn how a turbocharger increases the power output of an engine while surviving extreme operating conditions. We'll also learn how wastegates, ceramic turbine blades and ball bearings help turbochargers do their job even better. Turbochargers are a type of forced induction system. They compress the air flowing into the engine. The advantage of compressing the air is that it lets the engine squeeze more air into a cylinder, and more air means that more fuel can be added. Therefore, you get more power from each explosion in each cylinder. A turbocharged engine produces more power overall than the same engine without the charging. This can significantly improve the power-to-weight ratio for the engine.
In order to achieve this boost, the turbocharger uses the exhaust flow from the engine to spin a turbine, which in turn spins an air pump. The turbine in the turbocharger spins at speeds of up to 150,000 rotations per minute (rpm) -- that's about 30 times faster than most car engines can go. And since it is hooked up to the exhaust, the temperatures in the turbine are also very high.
Turbochargers and Engines
One of the surest ways to get more power out of an engine is to increase the amount of air and fuel that it can burn. One way to do this is to add cylinders or make the current cylinders bigger. Sometimes these changes may not be feasible -- a turbo can be a simpler, more compact way to add power, especially for an aftermarket accessory.
Turbochargers allow an engine to burn more fuel and air by packing more into the existing cylinders. The typical boost provided by a turbocharger is 6 to 8 pounds per square inch (psi). Since normal atmospheric pressure is 14.7 psi at sea level, you can see that you are getting about 50 percent more air into the engine. Therefore, you would expect to get 50 percent more power. It's not perfectly efficient, so you might get a 30- to 40-percent improvement instead.
One cause of the inefficiency comes from the fact that the power to spin the turbine is not free. Having a turbine in the exhaust flow increases the restriction in the exhaust. This means that on the exhaust stroke, the engine has to push against a higher back-pressure. This subtracts a little bit of power from the cylinders that are firing at the same time.
Turbocharger Design
The turbocharger is bolted to the exhaust manifold of the engine. The exhaust from the cylinders spins the turbine, which works like a gas turbine engine. The turbine is connected by a shaft to the compressor, which is located between the air filter and the intake manifold. The compressor pressurizes the air going into the pistons.
The exhaust from the cylinders passes through the turbine blades, causing the turbine to spin. The more exhaust that goes through the blades, the faster they spin.
On the other end of the shaft that the turbine is attached to, the compressor pumps air into the cylinders. The compressor is a type of centrifugal pump -- it draws air in at the center of its blades and flings it outward as it spins.
In order to handle speeds of up to 150,000 rpm, the turbine shaft has to be supported very carefully. Most bearings would explode at speeds like this, so most turbochargers use a fluid bearing. This type of bearing supports the shaft on a thin layer of oil that is constantly pumped around the shaft. This serves two purposes: It cools the shaft and some of the other turbocharger parts, and it allows the shaft to spin without much friction.
There are many tradeoffs involved in designing a turbocharger for an engine.
Turbocharger Parts
One of the main problems with turbochargers is that they do not provide an immediate power boost when you step on the gas. It takes a second for the turbine to get up to speed before boost is produced. This results in a feeling of lag when you step on the gas, and then the car lunges ahead when the turbo gets moving.
One way to decrease turbo lag is to reduce the inertia of the rotating parts, mainly by reducing their weight. This allows the turbine and compressor to accelerate quickly, and start providing boost earlier. One sure way to reduce the inertia of the turbine and compressor is to make the turbocharger smaller. A small turbocharger will provide boost more quickly and at lower engine speeds, but may not be able to provide much boost at higher engine speeds when a really large volume of air is going into the engine. It is also in danger of spinning too quickly at higher engine speeds, when lots of exhaust is passing through the turbine.
A large turbocharger can provide lots of boost at high engine speeds, but may have bad turbo lag because of how long it takes to accelerate its heavier turbine and compressor. Luckily, there are some tricks used to overcome these challenges.
Most automotive turbochargers have a wastegate, which allows the use of a smaller turbocharger to reduce lag while preventing it from spinning too quickly at high engine speeds. The wastegate is a valve that allows the exhaust to bypass the turbine blades. The wastegate senses the boost pressure. If the pressure gets too high, it could be an indicator that the turbine is spinning too quickly, so the wastegate bypasses some of the exhaust around the turbine blades, allowing the blades to slow down.
Some turbochargers use ball bearings instead of fluid bearings to support the turbine shaft. But these are not your regular ball bearings -- they are super-precise bearings made of advanced materials to handle the speeds and temperatures of the turbocharger. They allow the turbine shaft to spin with less friction than the fluid bearings used in most turbochargers. They also allow a slightly smaller, lighter shaft to be used. This helps the turbocharger accelerate more quickly, further reducing turbo lag.
Ceramic turbine blades are lighter than the steel blades used in most turbochargers. Again, this allows the turbine to spin up to speed faster, which reduces turbo lag.
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