Photo Sensors

Photo Sensors

A sensor is any device which can be used to measure a physical quantity and produces a signal for comprehension by the instrument or person who observes it. It finds a number of applications such as machines, robotics, cars, manufacturing and even medicine.

These devices can be effectively used in the manufacturing line to increase the productivity of factories. The sensitivity is measured based on the signals received and response provided to even minute deflections and variations. With the rise in technological innovations, different types of sensors are being introduced such as biometric sensors, photoelectric sensor, ultrasonic sensors, transducers etc.

Ultrasonic sensors are used to generate high frequency sound waves and the echo received back is evaluated. These types of transducers are also called transceivers. The working principle is also similar to sonar or radar. The electrical signals are transmitted by converting to sound signals and the echo is converted into electrical signals again by means of a transducer.

A photo sensor is an electronic device that can be used for detecting the presence of visible light, ultraviolet radiations and infrared radiations. The major component of such sensors is a semiconductor which possesses the property photo conductivity. These sensors are similar to bipolar junction transistor, diodes and field effect transistors. The only difference is the presence of transparent windows that allow the radiations to enter the semiconductor junction. This sensor is often referred to as photo electric sensor.

Photo sensors are classified into three types- opposed (through beam), retro reflective and proximity-sensing (diffused) type of photo electric sensors. In the opposed (through beam) type of photo electric sensors, the light beam is blocked from getting into the receiver from the transmitter and the objects are sensed.

The retro reflective sensor arrangement consists of the transmitter and receiver at the same side and the light from transmitter is bounced back onto the receiver. The sensing of objects takes place when the path of the light beam is obstructed. The proximity sensing photo sensor works on the principle of reflection of transmitted light off the object and reaches the receiver.

The operation of photo sensors is either light or dark. The light operation happens when the transmitter signal is received. The operation of dark operate photo eyes happen whenever the signal is not received by the receiver.

The operation of photo electric sensor requires only a power source. The concepts of optics and electronics are combined together in this device. It performs several operations such as amplification, demodulation, modulation etc.

The advantage of such sensors is the lesser space it consumes. The technological advances have led to the manufacture of more such smaller photo electric sensors.

Sensor deviations

Sensor Deviations

For other uses, see Sensor (disambiguation).
"detector" redirects here. For detector circuits in signal electronics, see detector_(radio).
"Sensors" redirects here. For other uses, see Sensors (disambiguation).
Sensor

Thermocouple sensor for high temperature measurement
A sensor (also called detector) is a converter that measures a physical quantity and converts it into a signal which can be read by an observer or by an (today mostly electronic) instrument. For example, a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass tube. A thermocouple converts temperature to an output voltage which can be read by a voltmeter. For accuracy, most sensors are calibrated against known standards.
Sensors are used in everyday objects such as touch-sensitive elevator buttons (tactile sensor) and lamps which dim or brighten by touching the base. There are also innumerable applications for sensors of which most people are never aware. Applications include cars, machines, aerospace, medicine, manufacturing and robotics.
A sensor is a device which receives and responds to a signal when touched. A sensor's sensitivity indicates how much the sensor's output changes when the measured quantity changes. For instance, if the mercury in a thermometer moves 1 cm when the temperature changes by 1 °C, the sensitivity is 1 cm/°C (it is basically the slope Dy/Dx assuming a linear characteristic). Sensors that measure very small changes must have very high sensitivities. Sensors also have an impact on what they measure; for instance, a room temperature thermometer inserted into a hot cup of liquid cools the liquid while the liquid heats the thermometer. Sensors need to be designed to have a small effect on what is measured; making the sensor smaller often improves this and may introduce other advantages. Technological progress allows more and more sensors to be manufactured on a microscopic scale as microsensors using MEMS technology. In most cases, a microsensor reaches a significantly higher speed and sensitivity compared with macroscopic approaches.

A good sensor obeys the following rules:

Is sensitive to the measured property only
Is insensitive to any other property likely to be encountered in its application
Does not influence the measured property
Ideal sensors are designed to be linear or linear to some simple mathematical function of the measurement, typically logarithmic. The output signal of such a sensor is linearly proportional to the value or simple function of the measured property. The sensitivity is then defined as the ratio between output signal and measured property. For example, if a sensor measures temperature and has a voltage output, the sensitivity is a constant with the unit [V/K]; this sensor is linear because the ratio is constant at all points of measurement.

Sensor directions

If the sensor is not ideal, several types of deviations can be observed:
The sensitivity may in practice differ from the value specified. This is called a sensitivity error, but the sensor is still linear.

Since the range of the output signal is always limited, the output signal will eventually reach a minimum or maximum when the measured property exceeds the limits. The full scale range defines the maximum and minimum values of the measured property.
If the output signal is not zero when the measured property is zero, the sensor has an offset or bias. This is defined as the output of the sensor at zero input.
If the sensitivity is not constant over the range of the sensor, this is called non linearity. Usually this is defined by the amount the output differs from ideal behavior over the full range of the sensor, often noted as a percentage of the full range.
If the deviation is caused by a rapid change of the measured property over time, there is a dynamic error. Often, this behavior is described with a bode plot showing sensitivity error and phase shift as function of the frequency of a periodic input signal.
If the output signal slowly changes independent of the measured property, this is defined as drift (telecommunication).
Long term drift usually indicates a slow degradation of sensor properties over a long period of time.
Noise is a random deviation of the signal that varies in time.
Hysteresis is an error caused by when the measured property reverses direction, but there is some finite lag in time for the sensor to respond, creating a different offset error in one direction than in the other.
If the sensor has a digital output, the output is essentially an approximation of the measured property. The approximation error is also called digitization error.
If the signal is monitored digitally, limitation of the sampling frequency also can cause a dynamic error, or if the variable or added noise changes periodically at a frequency near a multiple of the sampling rate may induce aliasing errors.
The sensor may to some extent be sensitive to properties other than the property being measured. For example, most sensors are influenced by the temperature of their environment.
All these deviations can be classified as systematic errors or random errors. Systematic errors can sometimes be compensated for by means of some kind of calibration strategy. Noise is a random error that can be reduced by signal processing, such as filtering, usually at the expense of the dynamic behavior of the sensor.
[edit]Resolution
The resolution of a sensor is the smallest change it can detect in the quantity that it is measuring. Often in a digital display, the least significant digit will fluctuate, indicating that changes of that magnitude are only just resolved. The resolution is related to the precision with which the measurement is made. For example, a scanning tunneling probe (a fine tip near a surface collects an electron tunneling current) can resolve atoms and molecules.

Types

Further information: Sense
All living organisms contain biological sensors with functions similar to those of the mechanical devices described. Most of these are specialized cells that are sensitive to:
Light, motion, temperature, magnetic fields, gravity, humidity, moisture, vibration, pressure, electrical fields, sound, and other physical aspects of the external environment
Physical aspects of the internal environment, such as stretch, motion of the organism, and position of appendages (proprioception)
Environmental molecules, including toxins, nutrients, and pheromones
Estimation of biomolecules interaction and some kinetics parameters
Internal metabolic milieu, such as glucose level, oxygen level, or osmolality
Internal signal molecules, such as hormones, neurotransmitters, and cytokines
Differences between proteins of the organism itself and of the environment or alien creatures.

Biosensor

In biomedicine and biotechnology, sensors which detect analytes thanks to a biological component, such as cells, protein, nucleic acid or biomimetic polymers, are called biosensors. Whereas a non-biological sensor, even organic (=carbon chemistry), for biological analytes is referred to as sensor or nanosensor (such a microcantilevers). This terminology applies for both in vitro and in vivo applications. The encapsulation of the biological component in biosensors, presents with a slightly different problem that ordinary sensors, this can either be done by means of a semipermeable barrier, such as a dialysis membrane or a hydrogel, a 3D polymer matrix, which either physically constrains the sensing macromolecule or chemically.

Sensor/Actuator Networks

Sensor/Actuator Networks

The proliferation of 'smart' energy management applications and the abundance of inexpensive, standards-based wireless MCUs are stimulating the growth of wireless sensor/actuator networks (WSAN) across diverse markets, including home and building automation, telemedicine, and lighting. Research firm IDTechEx forecasts a near ten-fold growth of the WSAN market, to $1.8B by 2019.

WSANs provide a simple, economic approach for the deployment of distributed monitor and control devices, avoiding the expensive retrofit necessary in wired systems. But inexperience with RF design and the confusing profusion of wireless protocols will continue to persist as some of the biggest challenges for the application developer. This article examines some of the basic concepts of wireless sensor networks and protocols, the essential elements comprising a wireless sensor, and some of the important design considerations for using them.

A wireless sensor and actuator network is a collection of small randomly dispersed devices that provide three essential functions; the ability to monitor physical and environmental conditions, often in real time, such as temperature, pressure, light and humidity; the ability to operate devices such as switches, motors or actuators that control those conditions; and the ability to provide efficient, reliable communications via a wireless network.

The implementation of this last capability is the most unique to WSANs. Since they are designed for low traffic monitor and control applications, it is not necessary for them to support the high data throughput requirements that data networks like Wi-Fi require. Typical WSAN over-the-air data rates range from 20 kbps to 1 Mbps. Consequently they can operate with much lower power consumption, which in turn allows the nodes to be battery powered and physically small.

WSANs are typically self-organizing and self-healing. Self-organizing networks allow a new node to automatically join the network without the need for manual intervention. Self-healing networks allow nodes to reconfigure their link associations and find alternative pathways around failed or powered-down nodes. How these capabilities are implemented is specific to the network management protocol and the network topology, and ultimately will determine the network’s flexibility, scalability, cost and performance.

Wireless sensor networks use three basic networking topologies; point-to-point, star (point-to-multipoint), or mesh. Point-to-point is simply a dedicated link between two points and arguably isn’t a network at all. Star networks are an aggregation of point-to-point links, with a central master node that manages a fixed number of slave nodes and serves as the conduit for all upstream communication.

Master nodes can also link with other master nodes to extend a star network into various configurations sometimes called cluster or cluster-tree networks.

One of the drawbacks of a star topology is that the master node is a single point of failure; if a master node fails, the entire sub-network fails. In the mesh topology, every node has multiple pathways to every other node, providing the most resiliency and flexibility. Most practical mesh networks utilize a type of pseudo-mesh with peer-to-peer communication links that support routing. Messages traverse the network using a multi-hop routing algorithm that can be optimized for the lowest latency or lowest power. Since each node in the mesh must maintain knowledge of other nodes in the network with routing tables, the memory requirements and processing overhead required at each node are higher in mesh networks.

Security Protocol for Sensor Networks

Security Protocol for Sensor Networks

Sensor networks are used in factories.
Sensor networks operate in industrial, utility process flow and environmental monitoring environments. Most sensor networks were expected to be contained within a single site like a factory, therefore few have security systems incorporated in them. The advent of wireless sensor networks, often used for security, creates a more sensitive environment to which security measures need to be applied.

 
Function
Sensors also are known as Remote Terminal Devices (RTUs). The most popular networking systems for these types are MODBUS, Profibus, DNP-3 and ICCP (Inter-Control Center Communications Protocol). None of these protocols include security systems. Wireless sensor networks also are used for security systems, detecting intruders and triggering alerts, or deterrents, like floodlighting.

Features
Sensors generally are low-power devices with little processing power. The demands of security systems are difficult to embed in such devices. TinySec is a lightweight encryption and authentication system that can be used for sensor networks without draining the power of sensor units. Encryption key distribution is another issue in these networks. LEAP and TinyPK are two key distribution systems suitable for wireless sensor networks.

Development

 

The notion of security has been overlooked in wired sensor networks due to the assumption that physical security of the network was sufficient. The introduction of wireless sensor networks sparked activity to provide sufficient security. This issue is an ongoing field of study.

 

Thoughts on Social Networking

Thoughts on Social Networking

One of the greatest boons of our lifetime is the incessant development in the information and communication technology or ICT. Amongst many other significant contributions to our life and society, this has also brought dramatic changes in the way we communicate i.e. think, write, talk, exchange ideas with each other. The changes are extremely pronounced in the language, style and the very medium over which we communicate.

Ever since computers and the Internet were found suitable as good means of communication, the idea of using them in mass communication kept floating. It was followed by numerous early ventures like e-mail, internet relay chat, video chat, collaboration, net meeting etc. All these ultimately ended up in what we know as social networking in today's world.

No other Internet-based invention soared so high and fast like social networking platforms. Facebook, Hi5, Orkut received tremendous response from Internet users. Few reasons for which these networking platforms received such huge attention are the ease of connectivity with friends and family, features like sharing of photo, video, music etc. and a host of useful applications, games etc.

Social networking has become a part of our daily (and sometimes the very first ) activity. There are many benefits of it. Besides the usual print and electronic media, platforms like Facebook, Google+, Twitter etc. are also playing important roles in communicating news and information which can even be more recent and accurate. The example of Arab Spring in 2011 says it all.

Looking at the other side of the coin, can we really find any menace of social networking. Some of us may be totally ignorant of the fact that these can sometimes be an evil all by itself. Because of the popularity and ease of access, social networking platforms are also suitable for harmful contents like cyber-crime, pornography, promotion of extremism etc.

I know I don't have problems with any of these malpractices. What I'm worried about is the 'privacy' question. There are accusations that the privacy of the users are at high risks at social networks. It is believed that, by means of unauthorised access or hacking our accounts, our privacy can be breached and manipulated for number of ill motives that can range from undesired disclosure of information to activities like identity thefts and thefts related to finance.

Despite all the wonderful features and numerous blessings, I see social networks as extremely risky due to few vulnerabilities and that keeps me keep my Facebook account closed.

It seems obvious that the Internet is an important tool for China as it continues to grow its economy.

The Internet is a way for Chinese companies to improve logistics for its manufacturing companies, to expose products to domestic and international markets, to help gather customers feedback, and to exchange ideas for business and personal growth. In fact, over 1 million Chinese citizens have accounts on LinkedIn, the social media site for business professionals.

With the Internet being such a valuable tool to keep the Chinese growth engine moving forward you might be asking why the Chinese government censors so many websites including Facebook, Twitter and LinkedIn; and, why many Google searches were blocked and why Google has to operate its search engine out of Hong Kong rather than somewhere else in mainland China.

So, what's going on in China regarding network equipment and the Internet and why is it happening?

Perhaps China is scared about internal descent, especially after seeing what is happening in other parts of the world. And, since China has certain provinces that are heavily Muslim, as well as, other potential problem spots like Tibet, maybe the Chinese think that censoring the Internet will offer them some type of protection. If they believe that, they are only delaying the inevitable. The people will find a way to communicate and they will mobilize even under the most difficult of situations. If you are not convinced of that just look at the current situation in Libya.

The Internet also offers China a way to connect with the world via manufacturing. And, with companies like Cisco establishing production of network equipment there, there is an even deeper connection to the Internet. Yet, it is well known that Chinese manufacturers reverse engineer products without regard to patents and counterfeit brand name products of all types and in all industries. The preponderance of counterfeit products even makes it way to the largest companies worldwide. About 1 year ago we were contacted by a Fortune 500 size company that wanted to sell us some of its used network equipment. They only buy equipment through Cisco's distribution system and so they do not purchase equipment, new or used, from the independent resale market. We worked out the deal and they sent us some Cisco cards. When they arrived here our expert Receiving Department and Tech Department compared them with products we knew were good and determined that these were counterfeit. We contacted the company we purchased them from (BTW, you would instantly recognize the company name if I told it to you) and alerted them that we were sending the cards back to them, since we purchased the cards from them, and that they should destroy them since we were certain they were counterfeit. The company was shocked since they were certain they had bought them through the legitimate manufacturers distribution channel. Both of our conclusions were that somehow counterfeits were substituted for real product in the distribution system. Neither of us could prove this but all the evidence sure pointed to that conclusion.

With everyone agreeing that China is manipulating its currency to have a trade advantage vs. other countries it is only a matter of time until this advantage goes away. Basic economics tells us that production will eventually move to the low cost producer. So, with China creating more wealth for its citizens it is only a matter of time until production costs rise and manufacturing is moved to another country or another continent. China will still be a huge consumer market but it's manufacturing production will disappear and it will become a service economy. And then, guess what? It will become the Asian version of the US economy.

Online Time Tracking Software

Online Time Tracking Software

Online time tracking software is a great way for you to take control of your time, see exactly where your time is being spend and more importantly see where your time can be saved.

Firstly a brief introduction into time tracking software. Time tracking software means the recording of amount of time you spend on a specific project, task, activity etc... and it can be used in many facets of both everyday and work life. A good example of it's use is when working on a project that contains many tasks. You may need to record exactly how much time you are spending on a specific task to be able to see how much time you have spent on a project as a whole. This becomes very important when thinking in terms of a provider/freelancer to client relationship.

Meeting the deadlines of your clients may not always be an easy feat as it is but to manually keep accurate track of your time while trying to hit deadlines makes things even harder, this is where online time tracking software really comes in useful. If you use online software to keep an accurate track of your time, it means one less thing you need to think about and all your attention can be focused on getting your projects completed in time.

An added bonus of using this software to track your time is a lot of the online applications contain additional features such as online invoicing. Software that includes an invoicing feature really takes away any headache you may have when it comes to converting your time into money when invoicing your clients. With online invoicing built into the application you will be able to quickly, easily and accurately bill your clients without the hassle you would normally have.

Time tracking applications may keep a record of your time in a timesheet allowing you to easily view the time spend on a certain task on a certain day easily and while a lot of online time tracking software is built with freelancers or single users in mind, that is not the case for all. Some also contain features which are useful for people working in teams, one such useful feature is timesheet approvals. time tracking applications which include timesheet approval features are great for teams or organisations who need to keep a closer track of how their team members time is being spent.

When it comes to choosing which online time tracking software is best for you there are several factors as mentioned to consider but what is for certain is tracking your time online is simple, quick and effective and can provide a powerful tool to help you manager your time better.

Blue Sky is a great free online time tracking application which also includes timesheet with approval facilities and online invoicing functions. It's a great tool for freelancers, teams and businesses alike.

Online Time Tracking & Management Software to Run Your Business

If you’re an owner or manager of a business, you know the frustrations that come with trying to best optimize you and your employees time. Time tracking and management software will monitor what is being accomplished ‘on the clock,’ so you can more efficiently manage time and productivity.

Today’s time tracking and management software does much more than the time clocks of old. These programs provide reports with all kinds of statistics and information to help you better run your business. Some suites even have financial features like invoices and integration with accounting programs.

01. Tenrox Timesheet Software

Tenrox Timesheet Software is easy to use and simple to configure. The web based timesheet system automates your project time tracking, time and attendance, time and labor for payroll, project costing, and client billing. Cloud-based timesheet software offers real time dashboards and reports so you can instantly see all project time, cost and billing information, execute and bill projects faster, make more informed decisions, reduce project time tracking,  time and attendance, and expense reporting overhead and administrative costs.

02. DOVICO Timesheet

DOVICO Timesheet is the only time tracking and management web–based software. DOVICO Timesheet software eliminates the time wasted, and inaccuracies of, manually recording data. It enables you to keep track of all work-related or billable time and makes it easy to prepare estimates on projects.

03. Web Time Sheet

Web TimeSheet from Replicon Inc. offers easy to use easy-to-use web timesheet software to track employee time, project time and expenses streamlining attendance, payroll, project tracking, costing and billing. It therefore provides, hassle free online timesheet management software and solutions to cater various business needs.

04. Pro Work flow

Proworkflow is an online web-based Project Managment tool with time tracking, timesheets, job costing, quotes and invoicing. The ProWorkflow solution has plans to suit many different business sizes. The top plan is a more comprehensive ‘Advanced’ solution developed to meet the requirements of corporate organizations from 50-1000+ users with multiple teams and divisions.

05. Timeless Time & Expense

Timeless Time & Expense is a Windows or Web application designed so you spend less time tracking and reporting and more time generating revenue.  Using a flexible hierarchy customized to the way you work, it is easy to track and invoice no matter how simple or complex your projects are. You can track you time using there web interface, Windows interface, or both.

06. ACE Project

Track hours entered by employees through a timesheet module. Time can be entered manually, in a standard timesheet, or automatically with a punch clock module. Project managers can generate time reports and view specific time tracking information. Simple, efficient and affordable Web-based project management software. Ideal for expense and project tracking. Features include time tracking, reporting, email notification, Gantt charts, access rights, document management, calendar and more.

07. ClickTime

Web timesheet and expense software made easy. ClickTime is the easiest way to track employee time and manage projects. you’ll always know which people are working on what projects. ClickTime has some practical bonus features to help organize your business, like the ability to manage your customers and contacts for all your projects. You can also specify your employee’s hourly rates and assign tasks.

08. Easy Time Tracking

All-in-one software for all time tracking needs. track employee timesheets, run billing reports and invoice clients. The time tracking and billing software that makes billing and invoicing so easy!

09. My Intervals

Intervals is web-based time tracking, task management, and project management for small businesses that need to know where all of their time is going. Includes workflow, timesheets, reporting, document storage, and invoicing. Intervals is ideal for small businesses — including designers, web developers, consultants, creative agencies, IT services firms, and communications companies that bill on an hourly or per project basis.

10. Invoicer

Online time tracking and invoicing software that helps you to effortlessly keep a track of time spend on each project and by each employee and keep track of the payments of these projects from the clients. Saves your time and helps you manage your bills in a snapshot. It is designed as a payment tracking application that helps you keep a track of your customer payments. You can send e-invoices to your clients with your business logo imprinted on them.

Communications

Telephone Systems:

Success in business need a lot of effort. Sometimes, even after investing a huge amount of money we cannot get the desired results. This implies that resource has to be channeled in the right direction to achieve success. The success of any business depends largely on its ability to satisfy customers.

Customers become satisfied when they receive a proper response to their queries. A company capable of providing a prompt solution to their clients has a long list of happy customers.

However, to be able to do that you need adequate staff and facilities. But what if you do not have them? Telephone answering service provides an excellent solution to deal with this situation. By using the service, your customers can have 24/7 access to your service through calls without having you to answer them. They employ trained telephone professionals who will answer your business calls professionally..

 

This will help to create a positive impression on your customers. Moreover, on using the script (that you provide), customers will think they are speaking to the company representative. This service is really helpful for small business owners who cannot afford to hire more staff and at the same time miss business calls.

Your virtual telephone receptionist operates from the office of the telephone service provider they work for. So, you need not clear any additional space for work in your place of business. Each call comes with some hidden opportunities for your business. Business answering service allows you to attend all your client calls. 

In the present economic scenario, you might prefer to answer all calls by yourself & use your answering machine to record missed calls. This will definitely save costs but what if your customers do not call back or leave messages. In the cut-throat competitive market, it might also happen that you missed a valuable sales opportunity just because you weren't there to answer it.

A small saving in cost might lead to huge loss in business. Relying on answering machine for unanswered calls has many disadvantages. Answering machine can record only as much information as provided by customers but cannot initiate a healthy exchange of information. 

They cannot answer customer queries or alert you on emergency calls. However, on using telephone answering service your virtual receptionist may conduct a general enquiry (with your permission), record all information correctly, and send you an instant alert of all calls through mails or messages. Failure of equipment is another factor that might affect your business if you depend on answering machine.

Now, if you think using business answering service will be a costly affair then you are wrong. There are many reputed companies in the UK which offer cost-effective packages on call answering service. You can avail the service on pay per call basis if you do not expect a huge amount of calls for your business.

And, if your business is in the growing phase and you receive a huge volume of calls everyday then you can avail the monthly packages.

There are certain reputed companies that offer call answering service starting at just 0.80p per call. So, stop relying on machine and double your profits with telephone answering service.