What You Can Model with the Heat Transfer Module

Conduction, Convection, and Radiation Analyses

The Heat Transfer Module can be used to study the three types of heat transfer in detail, expanding the analyses that are possible with the core COMSOL Multiphysics® simulation platform become aruba certified design expert.

Conduction

To describe conduction that occurs in any material, you can define the thermal conductivity as isotropic or anisotropic, and it may be constant or a function of temperature (or any other model variable).

Convection

Account for the motion of fluids in heat transfer simulations. You can use features for modeling pressure work; viscous dissipation; as well as forced and free (or natural) convection. Natural convection is automatically modeled when the gravity option is selected in the Single-Phase Flow interface.

Radiation

The Heat Transfer Module enables you to model surface-to-surface radiation using the radiosity method as well as radiation in participating media using the Rosseland approximation, P1 approximation or discrete ordinate method (DOM). The P1 approximation and DOM are also available for radiation in absorbing and scattering media, to model light diffusion in a nonemitting medium, for example. You can also model a radiative beam in absorbing media radiation using the Beer-Lambert law and couple the effect with other forms of heat transfer.

Temperature and velocity in an LED bulb

What You Can Model with the Heat Transfer Module

Whether heat transfer is the primary area of focus or part of a larger, complex analysis, you most likely need to examine multiple physical effects at once. With the multiphysics modeling capabilities of the COMSOL® software, you are able to perform complete and thorough analyses in one simulation environment, following a consistent workflow across physics. This intuitive approach to modeling and simulation can be used to account for heat transfer and all of the physical phenomena involved in your application.

Browse the following applications to see a small sample of what you can analyze and simulate with COMSOL Multiphysics® and the Heat Transfer Module.

Wi-Fi signal strength can be increased with aluminum foil

Scientists have discovered a simple and inexpensive way to increase the power of Wi-Fi signals inside our homes and this is based on the use of aluminum foil.

The researchers say that using a reflective screen made of aluminum foil, as a "virtual wall" positioned behind the Wi-Fi router, you can control the direction of propagation of wireless signals inside homes. This way we can improve the power of the wireless signal in a certain area of ​​our house.

"With this unique solution, we address a number of challenges affecting users of wireless technology."

"We have increased the power of wireless signals and made Wi-Fi connections safer," said researcher Xia Zhou of Dartmouth College, Hannover, New Hampshire.

Inspired by a simple method that would have succeeded in amplifying the wireless signal using a dose of beer, the researchers set out to study whether a similar solution could be used to optimally direct the wireless signal from the router dark fiber network.

Although there is some evidence that the use of an aluminum beer can, under certain conditions, can increase the intensity of wireless signals, this method involves making a curved aluminum panel as a reflector.

If we take into account the varied configuration of our homes, it is obvious that the solution of the location of such a reflector is not very scientific, because it does not offer an exact control over the place where the aluminum reflector directs the wireless signal.

To improve this solution, Zhou's team developed what is called WiPrint , a system that scans the interior or floor plan of your home to identify places where the Wi-Fi signal can be amplified, as well as areas where we don't need a signal. powerful wireless.

Based on this input data, the WiPrint algorithm can calculate the optimal shape of the signal reflector to be placed next to the Wi-Fi router. Subsequently, the reflector can be 3D printed in plastic and covered with aluminum foil.

The whole process of making the signal reflector takes about 23 minutes, and the only costs involved are to obtain the printed 3D frame.

"With an approximate investment of only $ 35 and the indication of wireless coverage requirements, we can make a custom reflector whose performance can be even higher than that of antennas that cost thousands of dollars," said Zhou.

The reflector made by the research team managed in tests to amplify the wireless signal by up to 55.1% in the areas where it was desired to increase its power and also managed to reduce the intensity of the wireless signal by up to 63.3% in areas where this was desired.

Aluminum foil signal reflector to increase Wi-Fi signal strength

Most of us will probably not be interested in lowering the power of the Wi-Fi signal. However, it is good to keep in mind that a high-intensity wireless signal that reaches outside our home can help malicious hackers. to take control of the wireless network we use in our home, although this risk is probably quite low.

Even if we do not have access to the researchers' algorithm for calculating the optimal shape of Wi-Fi reflectors based on the floor plan, nothing stops us from trying different forms of reflector to see if we can increase the signal coverage of the wireless network we use.

You only need to know that wireless signals must comply with certain technical regulations and, consequently, their modification, outside the permitted range, is prohibited.

"I can't really advise people to use aluminum foil or any other kind of reflector, mainly because of the regulations."

"In the US, FCC regulations set the power of wireless signals. Thus, the maximum power level of wireless routers is limited to a certain value ", said Eric Siu, Linksys product development director, who was not involved in this research.

Key features of F5 solutions

F5 Networks Careers

The hardware is designed specifically for the purpose of handling traffic.

Full-proxy architecture.

The ability to organize a universal system on a single platform.

The ability to divide resources into independent virtual devices within one physical one.

Communication capabilities: a large community of developers and users.

Tasks that F5 technologies will help solve

Resiliency and high availability of mission-critical applications.

Protection of web applications from DDoS attacks, Web Application Firewall.

Disaster recovery of data center solutions.

Consolidation of data centers, applications, data.

Optimal load balancing of applications.

Remote access to applications and / or network.

Implementation of complex application access schemes: BYOD, SSO.

Replacement of well-known EoS products: Cisco ACE and Microsoft TMG.

Refinement of the VDI architecture of VMware Horizon.

Formation of cloud infrastructure and applications (IaaS, SaaS).

Ready-to-use solutions for launching Microsoft, Oracle, HP, IBM, VMware, etc.

Ensuring PCI DSS Compliance.

Types of system administrators

System administrators can have a narrow focus and general (so-called generalists). System administrators with a general specialization are versed in various issues related to PC maintenance, and such specialists are most in demand in non-IT companies. It is more difficult for sysadmins with a narrow specialization to find a job, however, such specialists can solve the most complex problems and may be in demand in IT companies.

Types and types of system administrators: linux system

Web server administrator (in fact, this is the minimum knowledge of how to configure Apach, Nginx or IIS) 

Network administrator (more biased in networking - working with routers, VPN settings, etc.)

Network Security Administrator (anti-intrusion bias, running scanners to detect vulnerabilities, installing updates, etc.)

Administrator of mail servers (specializes in maintaining the health of mail servers, protecting users from unwanted emails, backups, working with quotas, etc.)

Additionally:

Database administrator (or DBA - in fact, has nothing to do with sysadmins and is exclusively engaged in tuning and working with a database, for example, Oracle)

Online sysadmin courses (beginners and advanced) at LinuxTrainingCenter

For sysadmins, the Linux Training Center has prepared an excellent course on learning Linux. The course "training for system administrators " includes:

After our course, you will gain practical skills of Linux system administrators at a level sufficient to perform all basic system administrator tasks (including practice in installing / configuring / administering Linux servers, setting up a network, configuring a Web server, etc.) 

CCNA4. Design and support of computer networks

The goal of this course is to help develop the skills required to design small corporate LANs and WANs. The course is a short tutorial on gathering information about customer requirements, choosing equipment and protocols based on those requirements, and creating a network topology to meet customer needs. Issues related to the creation and implementation of the proposed project for the client are also considered. The course aims to develop the practical skills required to work as Presales and Entry-Level Networking Professionals.

Upon completion of this course, you will receive information on the following topics: cisco wireless certified

the goal of proper network design;

Using the Cisco Network Lifecycle Method in Design;

methods of describing existing networks to prepare for their modernization;

the impact of various applications and services on network design;

requirements for the design of the central level, distribution and access levels for the enterprise complex, including wireless access and security;

design requirements for WAN connections at the enterprise edge and VPN support for remote workers;

testing and verification of the design of the network of the enterprise campus and the global network;

preparation and presentation to the client of a commercial proposal for network modernization.

An introduction to the concept of network design. Basics of network design. Design analysis at a central level. Analysis of distribution level issues. Analysis of design issues at the access level. Analysis of server farms and their protection. Analyze wireless network issues. Support for WAN and remote workers.

Determine network requirements. Implementing Cisco Lifecycle Services. Explanation of the sales process. Preparation for design. Determination of technical requirements and limitations. Define the design requirements for manageability.

Description of the existing network. Documenting the properties of an existing network. Upgrading an existing Cisco IOS OS. Modernization of existing equipment. Survey of the wireless area. Documenting the requirements for the network design.

Determine the impact of applications on the network design. Description of network applications. Basic network applications. Implementation of quality of service (QoS service). Analysis of voice and video capabilities. Traffic and application streams recording.

Network project creation. Requirements analysis. Choosing a suitable LAN topology. Designing WAN and remote worker support. Design of wireless networks. Enabling protective equipment.

Using IP addressing in the network design. Creation of an appropriate IP addressing project. Create an IP addressing and naming scheme. Description of IPv4 and IPv6.

Creation of a network prototype for a complex of buildings. Prototyping to validate the project. Prototyping for LAN. Prototyping a server farm.

Tests on a prototype WAN network. Testing a remote connection on a prototype. Testing WAN connectivity on a prototype. Testing support for remote workers on a prototype network.

How does fiber optics compare to electrical cables?

There are some technical areas, such as optical data transmission, where optical fibers compete with electrical cables, and there are other areas where fiber optic cables have significant advantages : How do fiber optics work

Optical cables are much lighter

Fiber capacity for data transmission is an order of magnitude higher

Signal attenuation can be very low

A large number of channels can be re-amplified in a single fiber amplifier

Fiber optic data transmission is difficult to intercept and manipulate, providing greater security

Fiber optic connections are immune to EMP

Fibers do not pose a fire hazard

However, fibers have disadvantages:

Optical connections are sensitive and difficult to handle. Alignment must be accurate and optimum cleanliness is required.

The fiberglass must remain relatively straight to prevent loss or breakage.

Overall, it is clear that the advantages outweigh the disadvantages, making fiber optics a remarkable innovation.

What are fiber optics used for?

We don't understand how ubiquitous fiber optic cables have become. The laser signals transmitted over these cables are hidden under the sidewalk and even under the ocean floor. The technologies that use these cables are as varied as the light signals themselves.

Computer networks

Fiber optic cables mainly carry information over long distances. This creates optimal conditions for data transfer. Fiber optic cables have many advantages over older styles of electronic transmission:

Less signal loss. Information travels 10 times further before it needs amplification

No interference. Fiber optic cables are less susceptible to electromagnetic interference

Higher throughput. Fiber optic cables carry much more data than older cables of the same size

Computers were once connected over long distances using telephone lines or Ethernet cables, but fiber optic cables have replaced these options because network computers with fiber optic cables are affordable, reliable, secure, and offer higher capacity.

Television and radio broadcasting

While early television and radio signals used electromagnetic waves to transmit signals, cable television companies moved forward using coaxial cables, which carried several analog television signals. As the number of cable TV consumers grew and television networks began to offer more channels and programs, cable operators switched from coaxial cables to optical fibers, from analogue to digital broadcasting.

Medical devices

Medical devices that help doctors look into human bodies without cutting them open were the first applications of fiber optics over 50 years ago. Gastroscopes and arthroscopes are commonplace in medicine today, and fiber optics continues to be an important component in new medical scanning and diagnostic devices.

Military use

Fiber optic cables are cheap, lightweight, high performance, thin, attack-resistant, and very secure. Thus, they provide an easy way to link military bases to missile launch sites and tracking radars. They do not emit electromagnetic radiation easily detectable by the enemy, and they are resistant when subjected to electromagnetic interference.

The relatively light weight of fiber optic cables compared to traditional wires is another advantage. Tanks, military aircraft, and helicopters began switching from metal cables to fiber optic cables. The savings in weight and cost are a big advantage, but fiber optics also increase reliability - their very nature makes them immune to electromagnetic pulse or other interference

We are building a Tier 3 data center using Cisco technologies

In order to get the maximum benefit from the investment, we decided to place our data centers in two highly secure colocation centers in Prague instead of building our own premises. It is a Tier 3 device with 99.982% uptime, which represents an interruption of 1.6 hours per year, and with N + 1 redundancy providing protection against power failure for 72 hours. 

Tier 3 is the highest level of infrastructure available in the Czech Republic. Customers can choose whether they want to use one or both of our data centers. For example, they can place a production environment in one and a disaster recovery backup in the other, or simply place everything in one location. In any case, they will receive highly available IaaS fully managed by Cloud4com with lightning-fast disaster recovery. 

From the very beginning, we have built our data center infrastructure on Cisco Unified Computing System (UCS) server technology, which is based on the standard Intel x86 architecture and supports both virtual and physical machines. Most importantly, the UCS system has allowed us to use blade servers that we can connect, disconnect and replace during full operation without downtime. 

Launched in 2009 when we launched Cloud4com, the Cisco UCS technology was only two years old, so it was still hot news. Many of our customers demanded its benefits, but without the cost of ownership. But we did not use the price as a differentiator. While renting UCS as part of the IaaS cloud services package cost less, the real advantage of our product was the features of the infrastructure itself, which offered both high availability and a higher level of security ccie data center salary. 

We work with Cisco to build trust

To reassure potential customers, we have emphasized the fact that we own the physical infrastructure and thus guarantee security ourselves. No one outside Cloud4com has access to our customers' cloud applications and data. This reassured especially IT managers who were still afraid of spying from times past. 

However, our partnership with Cisco is not limited to UCS. We recently upgraded the switches by moving from the Cisco Nexus 5000 Series to the 9000 Series, increasing throughput to 400 Gbps tenfold. We also use Cisco ASR 1000 aggregation routers to aggregate and encrypt network traffic, CSR 1000V cloud service routers to connect customers to our cloud, and Cisco ASA adaptive security devices for firewalls and network security applications. 

We operate almost exclusively on Cisco technologies and are one of its largest customers in the country. We used its technology to educate the Czech IT community and taught it to perceive and appreciate the benefits of cloud technologies and IaaS. To build a successful and scalable cloud IaaS solution, for us it meant to automate every process that is possible and to actively monitor the occurrence of events in the system and its use in real time. In this regard, Cisco's strategy has been a key factor in our success. Its approach is to ensure the availability and control of technologies in a software way, through well-defined APIs. This ensures consistency and speed of service delivery and high availability. It also allows us to provide customers with contractual guarantees of parameters while maintaining the economy of operation. 

In the last five years, we can observe an increase in demand for cloud technologies and IaaS among medium-sized companies. IT and CFOs come to taste the idea of ​​infrastructure as a regular monthly expense, similar to electricity or software licenses. 

Although this shift in attitudes partially stimulated the arrival of cloud services by Amazon and Microsoft, we are still considered a leader and pioneer in the field of IaaS in the Czech Republic.