Book Now Pay Later

Wednesday, January 3, 2018

Human Centric Lighting

Links and BackLinks

What is Human Centric Lighting?- An illuminating talk by Professor Warren Julian

Human Centric Lighting Design is an old Concept, given that our circadian clock runs on a 24 hour cycle. But It was difficult to maintain the circadian entrainment effectively with traditional lights. With the advent of LED, having expanded colour capabilities and seamless control on colour changes and dimming, a lot of research is underway to make our visual system respond more effectively to the light stimulus. Dynamic Tunable LED, varying the spectrum from 6500K to 2700K, has increased the circadian effectiveness of the human system. Increasing daytime alertness and nighttime sleep can be addressed in near future by acutely synchronizing the circadian system of human beings with proper doses of red and blue light. A brilliant presentation on Human Centric Lighting was made at Hong Kong International Lighting Fair 2017 by Professor Warren Julian of Sydney University. I have tried to reproduce the original talk as much as possible save for some very minor modifications. Hope you will enjoy reading it. So crisp and lucid that even a person with no knowledge on light and vision can gain rich insights into what Human Centric Lighting is? 

Hong Kong International Lighting Fair (Autumn Edition) 2017
Putting People First —
the Revolution of Human-centric Lighting
27th October 2017
Emeritus Professor Warren Julian,University of Sydney
Human-centric lighting:

its origins and implications

The Talk >>>>


 >  What lighting is about
› We see with our eyes (part of our brain)
› Two visual systems plus one for our body clock
› We are really daytime people
› This is what you really see
› Revealing contrast
› What human-centric lighting is
› Concluding remarks

    What lighting is about

“flow” of light — not just downwards; revealing (sky)light and directional (sun)light; sky and sun have all λ and do not flicker

We see with our eyes (part of our brain)

Two visual systems plus one for our body clock
We don’t see all colours equally


We are really daytime people

We walked out of the forest
and onto plains to become a
›We are a daytime predator
with very good vision
›Our eyes are designed for
›We cannot see at night
›We are frightened of the

›We used to go to sleep after dark

This is what you really see

This is due to Retinal Eccentricity.

Retinal eccentricity is due to the differing pattern of response to light stimulation across the retina due to different conditions and the different densities and ratio of rods and cones across the surface.

Cone sensitivity varies over the visual field in the presence of a uniform photopic background and sensitivity falls off in the parafovea from a sharp foveal peak, then declines more gradually toward the periphery

We must detect contrast to find edges

Seeing must
have meaning                                                                                     

What human-centric lighting is

Philips, for example, gives a definition on its Lighting University Resource Browser:
Human-centric lighting is lighting devoted to enhancing
vision, wellbeing, and performance individually or in
some combination

This suggests there are three
essential elements:
enhancing human vision,
wellbeing and

Lighting has always been human-centric

In fact, it cannot be other than human-centric because the photometric units (lumen, lux, etc) are all based on the human (only) response to light.
Lighting standards are predicated on providing good seeing conditions,which encompasses “enhancing vision”, “performance”, through a sufficiency of light and the minimisation of performance reducing effects such as glare and unwanted reflections, and “wellbeing” by lighting the environment as well as the tasks using appropriate light in terms of CCT and CRI.
Competent Lighting Designers were aware of the circadian role of lighting before the recent discovery of the physiological mechanisms involved.

That meaningless word “wellbeing”

“Wellbeing”, enthusiastically embraced by the alternative medicine and cosmetics industries, has become a byword for many in the lighting industry.

› Good lighting can produce a feeling of wellbeing by good design and by reducing unwanted effects such as glare.
› However, greatest impediments to wellbeing in most workplaces are:
- is poor task design , eg, allowing insufficient time to complete the task’s visual component
- by asking people to work when their circadian cycle is calling for rest or sleep
- by not providing distance views that allow the intraocular muscles to relax,
- by not providing views of the outside that are both visually stimulating and allow the perception of the passage of time.
› Superficial electric lighting colour changes and other control tricks probably exacerbate these problems, rather than ameliorating them.

Concluding Remarks

The birth of a new concept Li-Fi

Light Fidelity or Li-Fi is a Visible Light Communications (VLC) system running wireless communications travelling at very high speeds.
Li-Fi uses common household LED (light emitting diodes) light bulbs to enable data transfer, boasting speeds of up to 224 gigabits per second.

wifi istock themacx

The term Li-Fi was coined by University of Edinburgh Professor Harald Haas during a TED Talk in 2011. Haas envisioned light bulbs that could act as wireless routers.
Subsequently, in 2012 after four years of research, Haas set up company pureLiFi with the aim 'to be the world leader in Visible Light Communications technology'
(Information on Li-Fi is from a different source, as I was not able to reproduce the images shown by Prof Warren Julian in his talk)
- Courtesy : Prof Warren Julian


Tuesday, December 19, 2017

A Caledonian Experience

Links and BackLinks
Scotland - Part 1

King’s Cross Station, London. One of the oldest and busiest railway stations of Europe, located in central London. During the inaugural period(1851) Queen Victoria travelled to Scotland from this station. We took the morning high speed train from here on our journey to Caledonia. Caledonia is the Latin name given by the Romans in early first century AD for area north of their province Britannia. The train sped through the rolling English countryside. And from Newcastle upon Tyne the scene was more breathtaking, as the train ran almost along the North Sea, its beaches and cliffs.  Before coming to Scotland I personally carried an impression that Edinburgh is a quaint little Scottish town, and its rail station is small and compact, like any other wayside stations in England. But as we stepped down on the platform I was stupefied to find a vast complex teeming with people. The station is well connected to the North Bridge, which runs over the station and bridges the new town with the old town. The old town belongs to the Georgian era whereas the new town came up during the Victorian era. The entire Edinburgh, in fact, is steeped in history. If you walk along the main thoroughfare of the city you will find tall buildings on both sides of the street, all around 300 to 400 years old and all of chocolate shades. They are strong and sturdy, impervious of the ravages of time. All these skyscraper type buildings came up when Cromwell’s men filled up the city and had to be accommodated. In fact Edinburgh is considered one of the forerunners of modern day skyscraper. What is appealing is that these buildings are utilized for commercial spaces, hotels, restaurants and even private residences. In other words the modern utilities and furnishings have been subtly integrated in the interiors while retaining the old look on the exterior. Like London, Edinburgh also has a very efficient fleet of double decker buses. Only the colour, instead of red it is chocolate brown. Scottish boasts of sandwiches and there are a lot of sandwich shops in the city. One such shop was right across the street where our hotel was located. I enjoyed cheese and ham sandwich with beer over there. A big poster inside the shop momentarily tempted me for a trip to the Real Mary King’s Close located in Royal Mile, Old town near the station and quite close to our hotel. Real Mary King’s Close happens to be streets found deep beneath Royal Mile, and tourists are taken through a guided tour to explore the past lives of people living there. Unfortunately the vertigo in me made me opt out of this . Next morning was exclusively for conducted trip to Scottish Highlands, Loch and Whiskey. Early next morning we reached Nero’s Caffé, near Edinburgh Castle, for our Scottish Highlands tour. It’s a warm little café with refreshing coffee aroma dominating the space. While waiting for our bus we had cakes and coffee. A small, around 20 seated bus, with proper audio arrangements, so that the driver cum tour guide can narrate while driving on various sites on our way to Scottish Highlands..The first stopover was Forth Rail Bridge, about 10 km from Edinburgh.. One of the first cantilever bridge, built in 1890, after the original Tay bridge collapsed when a train was passing over it resulting in heavy casualty. It is a technological marvel. This two and a half kilometer Iron Bridge across Firth of Forth estuary is one of the safest and heaviest bridges on earth. The dark red iconic bridge has a very strange and complex look .We were also lucky to see a train passing over it.


Concourse of King's Cross main station

An exterior view of King's Cross rail station

Virgin East Coast Train

View from train

View from train

Along the North Sea after Newcastle upon Tyne



The Bridge connecting new town to old town of Edinburgh  
Nero's Cafe

Edinburgh Castle

Forth Rail Bridge

Photographs : Arundhati Sengupta

Plan your trip to Scotland

If you are planning a short trip for a day or two from London, the most recommended option is by train. There are some comfortable, high speed trains run by Virgin East Coast. These trains start from Kings Cross station in Central London and takes around four and a half hour to reach Edinburgh. Since demand is pretty high for these trains, it is suggested to book tickets in advance, which can be done online from any part of the globe through the site   For a comfortable stay while in Scotland book through the link:  

Plan your Stay in UK with

Tuesday, November 28, 2017


Links and BackLinks

From Ruby’s Kitchen

Fish – 2 whole pcs (medium size)
Ginger Paste – 1 tsp
Onion Paste – 1 tbsp
Black Pepper(crushed) – 1 tbsp
Olive Oil – 1.5 tbsp
Parsley (finely chopped) – 1 tbsp
Salt – 1.5 tbsp
Vinegar - 1 tbsp
Lemon – 2 pcs
Besan – half tsp
Capsicum, tomato, cauliflower, beans - all chopped into tiny cubes

Method of Preparation.
Clean fish and keep it soaked for about one hour in vinegar, lemon juice (two medium sized fresh lemons) and 1 tablespoon salt. After that wash the fish thoroughly and then dry it with towel napkin. Marinate the fish with onion paste, ginger paste, salt and parsley, preferably for about two hours. Once marinated, apply a thin layer of Besan coating on the entire fish. Then place the fish in one table spoon oil on a frying pan, cover it with a lid and let it fry in low flame for, say 10 minutes,. Next, flip the fish to the other side, apply half teaspoon black pepper and continue the frying process for 10 minutes. After that turn the fish again, apply rest of the black pepper on the the exposed side, raise the flame, place all vegetables in the frying pan and fry each side of the fish for two minutes. Try to keep the pan covered with lid when frying takes place. Pour rest of the lemon juice once the frying is over, and your fried sardine is ready. Bon appétit!

Cheesy Variation

Cover the fried fish with one tablespoon of grated Parmesan cheese and a sprinkle of crushed black pepper. Place the lid for one minute to allow the cheese to melt over the fish. Serve the dish with toast. Bon Appétit!

The Process Pics

 Photographer : Arundhati Sengupta (Recipe & photographs are from her Kitchen Diary)


Friday, October 20, 2017

Cinque Terre

Links and BackLinks

Simply enchanting! A sight that provokes a longing to return again and again. As our train passed through a series of tunnels after La Spezia and was about to enter Riomaggiore station, the openings in the tunnel walls provided a fleeting view of the precipice leading almost vertically down to a spectacular expanse of blue Mediterranean.Crystal blue, totally different from colours of seas I have seen so far. So distinct that this shade of blue has come to be known as Mediterranean Blue. Riomaggiore is one of the five villages on the rugged portion of Italian Riviera. The other four villages are Monterosso al Mare, Vernazza, Corniglia and Manarola. All these five villages and the surrounding hillsides dot the Riviera and belong to Cinque Terre (meaning ‘five lands’) National Park – a UNESCO World Heritage site. Since almost thousand years from now, residents of these villages carved terraces on the rugged and steep rocky lands right upto the cliffs. These heavily terraced hills were used to cultivate grapes and olives. And today this region flourishes for its vineyards, some of the best Italian wines, olives and fishing.

Riomaggiore Rail Station

Mediterranean Sea

A view of the Riviera

Cinque Terre

Blue sea

Tunnel leading to the beach at Riomaggiore

Shop for water sports equipments

Water sports equipments are available on rental for tourists




Mediterranean Blue

Map of Cinque Terre National Park, UNESCO World Heritage site

Cafes and shop selling souvenirs and local wares

Riomaggiore beach area

Houses at Riomaggiore

Cinque Terre


Photographs : Arundhati Sengupta

How to get to Cinque Terre from Florence ( Firenze )
There are several trains run by Trenitalia from Florence to Pisa and from Pisa to La Spezia. In order to travel to Riviera and Cinque Terre from Florence, one can plan out a comfortable day visit. Buy a ticket at Florence Rail Station for your journey to Riomaggiore. Florence is a very friendly station and buying a ticket is an easy task. Change trains at Pisa and La Spezia. Florence to Pisa takes less than an hour, while Pisa to La Spezia takes around one hour and La Spezia to Riomaggiore about ten minutes.

As Cinque Terre region is heavily terraced upto the cliffs no motorable roads came up over the centuries due to ruggedness and complexities of the Italy’s landmass along the Mediterranean Sea. In absence of such corporate development, the region has retained its pristine beauty. But Italian Railways has done a great job in providing connections to these five villages which otherwise was largely cut off from the larger world. Prior to rail service, boat was the only lifeline linking the isolated communities to the larger world. Railways have made properly guarded pathway around the cliff walls for a spectacular view of the Mediterranean lapping úp against the rocky shores, and also a tunnel running parallel to train tunnel for tourists to take a shorter and easier route to sea level.There are three to four cafes on the riviera where one can enjoy delectable seafood and Italian wine. Washrooms are located near the cafes and at Riomaggiore station where entry fee per person  is one euro. The other shops located at the shore end of the tunnel cater to water sports products like kayaks,scuba diving equipments etc. on rental, nice souvenirs and local products.If you plan your stay in La Spezia or any of the Cinque Terre towns you may click the following link to book your stay.

Book Now Pay Later for your Hotels or Apartments in Italy

expedia for hotels

click here